First Edition, 2007
ISBN 978 81 89940 56 0
© All rights reserved.
Published by: Global Media 1819, Bhagirath Palace, Chandni Chowk, Delhi-110 006 Email:
[email protected]
Table of Contents 1. Periodic Table 2. Alkali Metals 3. Atoms and Molecules 4. Water 5. Organic Molecules 6. Dictionary
General Periodic Table 1
2
3
4
5
6
7
8
9
10
11
12
H 1 Hydrogen
2 3
Li
Be
Lithium
Beryllium
Na
Mg
Sodium
Magnesium
K 4 Potassium
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Calcium
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
Strontium
Yttrium
Zirconium
Niobium
Molybdenum
Technetium
Ruthenium
Rhodium
Palladium
Silver
Cadmium
Cs
Ba
*
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Cesium
Barium
Hafnium
Tantalum
Tungsten
Rhenium
Osmium
Iridium
Platinum
Gold
Mercury
Fr
Ra
Rf
Db
Sg
Bh
Hs
Mt
Uun
Uuu
Uub
Francium
Radium
Rb 5 Rubidium
6 7
A
**
T
Unnilquadium Unnilpentium Unnilhexium Unnilseptium Unniloctium Unnilennium Ununnilium Unununium Ununbium
* **
La
Ce
Pr
Nd
Lanthanum
Cerium
Ac
Th
Pa
U
Actinium
Thorium
Protactinium
Uranium
Pm
Sm
Eu
Gd
Tb
Samarium
Europium
Gadolinium
Terbium
Np
Pu
Am
Cm
Bk
Neptunium
Plutonium
Americium
Curium
Praseodymium Neodymium Promethium
Dy
Berkelium Ca
Element Groups (Families) Alkali Earth Alkaline Earth Transition Metals Rare Earth Other Metals Metalloids Non-Metals Halogens Noble Gases
Name wise Periodic Table 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1
H
He
1
2
2
Li Be
B
C N O
F Ne
3
5
6
9
3
Na Mg
Al Si P
11 12
13 14 15 16 17 18
4
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
4
19 20 21 22 23 24 25 26 27
28
29
30
7
8
10
S Cl Ar
31 32 33 34 35 36
5
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 37 38 39 40 41 42 43 44 45
46
47
6
Cs Ba * Hf Ta W Re Os Ir
Pt
Au Hg Tl Pb Bi Po At Rn
55 56
78
79
7
Fr Ra ** Rf Db Sg Bh Hs Mt Uun Uuu Uub
72 73 74 75 76 77
87 88
48 80
I Xe
49 50 51 52 53 54 81 82 83 84 85 86
104 105 106 107 108 109 110 111 112 * La Ce Pr Nd Pm Sm Eu 57 58 59 60 61 62 ** Ac Th Pa
63
Gd Tb Dy Ho Er Tm Yb Lu 64
65
66 67 68 69 70 71
U Np Pu Am Cm Bk Cf Es Fm Md No Lr
89 90 91 92 93 94
95
96
97
98 99 100 101 102 103
Element Groups (Families) Alkali Earth
Alka Tran line sition Eart Meta
h ls Othe Meta r Met lloids als Nobl Halo e gens Gase s
Rare Earth
Non-Metals
1 2 3 4 5 6 7 8 9
1 1 1 1 1 1 1 1 17 0 1 2 3 4 5 6 8
1H
He
1.007 94
2
Li
4.00 2602
B e
B C N O
9.01 6.941 218 2
Na
3
10.8 11
M g
4
C M F N Sc Ti V Cr Co Cu Zn Ga Ge As Se Br Kr a n e i
Rb Sr Y Zr
5
65.3 9
72.6 74.9 78.9 79.90 83.8 1 2160 6 4 0
10 102. 106 107. 112. (98) 1.0 9055 .42 8682 411 7 0
114. 818
118. 710
121. 760
127. 126.9 131. 60 0447 29
B O * Hf Ta W Re Ir Pt Au Hg Tl Pb Bi Po At Rn a s
132.9 137. 0545 327
180. 178. 183. 947 49 84 9
19 195 196. 208. 186. 192. 200. 204. 207. 0.2 .07 9665 9803 (209) (210) (222) 207 217 59 3833 2 3 8 5 8
U R D H Uu Uu 7 Fr a ** Rf b Sg Bh s Mt u u b n (223)
69.7 23
N M R P Tc Rh Ag Cd In Sn Sb Te I Xe b o u d
92.9 85.46 87.6 88.9 91.2 95.9 063 78 2 0585 24 4 8
6
S Cl Ar
26.9 30.9 28.0 32.0 35.45 39.9 8153 7376 855 66 27 48 8 1
44.9 54.9 55. 58.9 58. 39.09 40.0 47.8 50.9 51.9 63.5 5591 3804 84 3320 693 83 78 67 415 961 46 0 9 5 0 4
Cs
12.0 14.0 15.9 18.99 20.1 107 0674 994 84032 797
Al Si P
22.98 24.3 9770 050
K
F Ne
(226 )
(261 (262 (26 (26 (263) (262) (266) (272) (277) ) ) 5) 9)
* La
C P S E T Pr Nd Gd Tb Dy Ho Er Yb Lu e m m u m
138. 140. 151 158. 164. 168. 140. 144. (14 150. 157. 162. 167. 173.0 174. 905 9076 .96 9253 9303 9342 116 24 5) 36 25 50 26 4 967 5 5 4 4 2 1
**
A T N A C F M Pa U Pu Bk Cf Es No Lr c h p m m m d 232. 231. (227 238. (23 (24 038 0358 (244) (247) (247) (251) (252) (257) (258) (259) (262) ) 0289 7) 3) 1 8
Element Groups (Families) Alka line Eart h Othe r Meta ls Halo gens
Alkali Earth
Rare Earth
Non-Metals
1 2 3 4 5 6 7 8 9
1 1 1 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8
1 H1
He 2
2 Li 2,1
Be 2,2
2,3
Na
M g
Al Si P S Cl Ar
2,8,1 2,8,2
2,8,3 2,8,4 2,8,5 2,8,6 2,8,7 2,8,8
K Ca
S M Ti V Cr Fe Co Ni Cu Zn Ga Ge As Se Br Kr c n
3 4
B C N O F Ne 2,4
2,5
2,6
2,7
2,8
2,8,8 2,8,8 2,8, 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 ,1 ,2 9,2 0,2 1,2 3,1 3,2 4,2 5,2 6,2 8,1 8,2 8,3 8,4 8,5 8,6 8,7 8,8
Rb Sr Y Zr
52,8,1 8 8,1
N M A Tc Ru Rh Pd Cd In Sn Sb Te I Xe b o g
2,8,1 2,8, 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 8 18 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8,2 9,2 10,2 12,1 13,1 14,1 15,1 16,1 18,0 18,1 18,2 18,3 18,4 18,5 18,6 18,7 18,8
Trans ition Metal s Metal loids Noble Gases
Cs Ba * Hf Ta W Re Os Ir Pt
62,8,1
2,8,1 8 8 18,8, 18,8, 1 2
Fr Ra
72,8,1
A H Tl Pb Bi Po At Rn u g
2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,18 0,2 1,2 2,2 3,2 4,2 5,2 7,1 8,1 8,2 8,3 8,4 8,5 8,6 8,7 ,8
* D U U U Rf Sg Bh Hs Mt * b un uu ub
2,8,1 8,32 8,32 18,8, 18,8, 1 2
2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 32,1 0,2 1,2 2,2 3,2 4,2 5,2 7,1 8,1 8,2
* La Ce Pr
N P S G D H T Y Eu Tb Er Lu d m m d y o m b
2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 18,9, 20,8, 21,8, 22,8, 23,8, 24,8, 25,8, 25,9, 27,8, 28,8, 29,8, 30,8, 31,8, 32,8, 32,9, 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
N A C F M N * Ac Th Pa U Pu Bk Cf Es Lr * p m m m d o 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 2,8,1 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 8,32 18,9, 18,1 20,9, 21,9, 23,8, 24,8, 25,8, 25,9, 26,9, 28,8, 29,8, 30,8, 31,8, 32,8, 32,9, 2 0,2 2 2 2 2 2 2 2 2 2 2 2 2 2
Element Groups (Families) Alkali ne Earth Other Metals Haloge ns
Alkali Earth Rare Earth Non-Metals
1 2 3 4 5 6 7 8 9 10 11 12
1 1 1 1 1 18 3 4 5 6 7
1 H0 2
He 2
Li
B e
4
5
N M 3a g 12
12
B C N O F Ne 6
6
7
8
10
10
Al Si P S Cl Ar 14
14
16
16
18
22
Transiti on Metals Metallo ids Noble Gases
4K 20
R
5b
48
C S M C G G A Ti V Cr Fe Ni Cu Zn Se Br Kr a c n o a e s 20
24
26
28
28
30
30
32
31
35
35
39
41
42
45
45
48
Sr Y
Z N M R R S S Tc Pd Ag Cd In Te I Xe r b o u h n b
50
51
50
52
54
55
57
58
60
61
64
66
69
71
76
74
77
C B H T R O P * W Ir Pt Au Hg Tl Bi Po At Rn f a e s b 6s a
7
78
81
106 108 110
Fr
R * R D B H M Uu Uu Uu Sg a * f b h s t n u b
136 138
157 157 157
*
111
155
114 115
157 157
117
159
118
161
121
123 125 126
125
125
136
165
L C N P S D H T Y Pr Eu Gd Tb Er Lu a e d m m y o m b 82
82
82
84
84
88
89
N P A * A T Pa U * c h p u m 138 142 140
146
144 150
148
93
94
97
98
99
100
103
104
C F M N Bk Cf Es Lr m m d o 151
150
153 153 157
157
157
159
Element Groups (Families) Alkali ne Earth Other Metals Haloge ns
Alkali Earth Rare Earth Non-Metals
1 2 34 5 6 7 8 9
1 1 1 1 1 1 1 11 18 0 2 3 4 5 6 7
H
He
1 259.-
-272
14
Li
2
B e
180. 127 54 8
B C N O F Ne 2300
350 209. 218. 219. -248.6 0 9 4 62
Transit ion Metals Metallo ids Noble Gases
3
4
N M a g
Al Si P S Cl Ar
97.8 650
660. 141 112. 44.1 100. -189.3 37 0 8 98
K
C S T M C G G A V Cr Fe Ni Cu Zn Se Br Kr a c i n o a e s
63.6 153 166 189 185 124 153 149 419.5 29.7 937. 839 1453 1083 817 217 5 9 0 0 7 5 5 5 8 8 4
5
-7.2 -157.2
R Z N M T R R S S T Sr Y Pd Ag Cd In I Xe b r b o c u h n b e 38.8 152 185 246 261 220 225 196 961.9 156. 231. 449. 113. 764 1552 320.9 630 -111.9 9 3 2 8 7 0 0 6 3 61 9 5 5
6
Cs
B H T R O P P * W Ir Pt Au Hg Tl Bi At Rn a f a e s b o 215 299 341 318 304 241 1064. 303. 327. 271. 1772 254 0 6 0 0 5 0 43 38.87 5 5 3
28.5 725
7
Fr
R * R D S B H M Uu Uu Uu a * f b g h s t n u b
27
700
?
*
?
?
?
?
?
?
?
302
-71
?
L C N P S D H T Y Pr Eu Gd Tb Er Lu a e d m m y o m b 920 795 935
101 0
?
107 2
822
1311 1360 1412
147 152 154 0 2 5
824
1656
N P A C F M N * A T Pa U Bk Cf Es Lr * c h p u m m m d o 105 175 160 113 639. 640 0 0 0 2 5
994
1340
?
?
?
?
?
?
?
Element Groups (Families) Alkali Earth Rare Earth Non-Metals
1 2 34 5 6 7 8 9 H
Alkali ne Earth Other Metals Haloge ns
1 1 1 1 1 1 1 1 18 0 1 2 3 4 5 6 7 He
Transit ion Metals Metallo ids Noble Gases
H
He
1 252.-
-268.6
87
Li
B e
B C N O F Ne
1347
297 0
255 482 195. -183 188. -246.1 0 7 8 14
2
3 4 5 6
N M a g
Al Si P S Cl Ar
552. 110 9 7
246 235 444. 280 -34.6 7 5 6
K
C S T M C G G A V Cr Fe Ni Cu Zn Se Br Kr a c i n o a e s
774
148 283 328 338 267 4 2 7 0 2
196 275 287 2732 2567 2 0 0
907
240 283 684. 58.7 613 -153.4 3 0 9 8
R Z N M R R S S Sr Y Tc Pd Ag Cd In Te I Xe b r b o u h n b 688
138 333 437 492 461 4 7 7 7 2
Cs
B H T R O P * W Ir Pt Au Hg Tl Bi Po At Rn a f a e s b
678. 114 4 0
7
-186
540 542 566 0 5 0
487 390 372 2927 2212 7 0 7
765
562 502 452 356.5 145 174 156 3827 2807 962 7 7 7 8 7 0 0
Fr
R * R D B H M Uu Uu Uu Sg a * f b h s t n u b
677
173 7
?
*
?
?
200 227 175 989. 184 0 0 0 8
?
?
?
?
?
337
-108.1
-61.8
?
L C N P S D H T Y Pr Eu Gd Tb Er Lu a e d m m y o m b 346 325 312 9 7 7
312 7
?
190 256 272 251 172 1597 3233 3041 1466 0 2 0 0 7
3315
N P A C F M N * A T Pa U Bk Cf Es Lr * c h p u m m m d o 320 479 0 0
?
381 390 323 2607 8 2 5
?
?
?
?
Element Groups (Families) Alkali Earth Alkaline Earth Transition Metals Rare Earth Other Metals Metalloids Non-Metals Halogens Noble Gases
?
?
?
?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2
H
He
Hex
Hex
Li Be Cub
B
Hex
C N O
Rhom Hex
Mg 3 Na Cub Hex
Hex
Al Si P Cub
Cub
F Ne Cub
Cub
S Cl Ar
Cub Mono Ortho Ortho Cub
K Ca Sc Ti V Cr Mn Fe Co Ni
Cu Zn Ga Ge As Se Br Kr
Cub
Cub
Cub
5 Rb Cub
Sr Y Zr Nb Mo Tc Ru Rh Pd
Ag Cd In Sn Sb Te
Cub
4
Hex Hex
Cub
Hex
Cub
7
Fr Ra ** Rf Db Sg Bh Hs Mt Uun Uuu Uub Cub
?
?
?
?
?
?
?
* La Ce Pr Nd Pm Sm Eu Hex
Cub
Hex
** Ac Th Pa Cub
Cub
Hex
Hex
Rhom
Cub
?
Hex
Cub Rhom Mono
Rhom
Rhombohedral
Cub
Cubic
Mono
Monoclinic
Ortho
Orthorhombic
Tet
Tetragonal
?
Unknown
?
Cub
?
Gd Tb Dy Ho Er Tm Yb Lu Hex
Hex
Hex
Hex
Hex
Hex
?
?
?
?
Crystal Structure Abbreviations Hexagonal
Ortho Cub
Hex
Cub
Hex
U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Ortho Ortho Ortho Mono
Hex
Hex
I Xe
Cub
Rhom
Rhom
Ortho Cub
Cub
Cub
Tet
Hex
Au Hg Tl Pb Bi Po At Rn
Hex
Tet
Cub Rhom
Pt
Hex
Hex
Ortho
Cs Ba * Hf Ta W Re Os Ir Cub
Hex
Cub
6
Cub
Hex
Hex
Cub
Cub
Cub
Cub
Cub
Hex
Cub
Cub
Cub
Cub
Hex Hex
Cub
Element Groups (Families) Alkali Earth Alkaline Earth Transition Metals Rare Earth Other Metals Metalloids Non-Metals Halogens Noble Gases
?
?
?
?
Alkali Metals The alkali metals, found in group 1 of the periodic table (formerly known as group IA), are very reactive metals that do not occur freely in nature. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements. As with all metals, the alkali metals are malleable, ductile, and are good conductors of heat and electricity. The alkali metals are softer than most other metals. Cesium and francium are the most reactive elements in this group. Alkali metals can explode if they are exposed to water. The Alkali Metals are: • • • • • •
Lithium Sodium Potassium Rubidium Cesium Francium
Basic Information Name: Lithium Symbol: Li Atomic Number: 3 Atomic Mass: 6.941 amu Melting Point: 180.54 °C (453.69 K, 356.972 °F) Boiling Point: 1347.0 °C (1620.15 K, 2456.6 °F) Number of Protons/Electrons: 3 Number of Neutrons: 4 Classification: Alkali Metal Crystal Structure: Cubic Density @ 293 K: 0.53 g/cm3 Color: silvery
Atomic Structure
Number of Energy Levels: 2 First Energy Level: 2 Second Energy Level: 1
Isotopes Isotope
Half Life
Li-6
Stable
Li-7
Stable
Facts Date of Discovery: 1817 Discoverer: Johann Arfvedson Name Origin: From the Greek word lithos (stone) Uses: batteries, ceramics, lubricants Obtained From: passing electric charge through melted lithium chloride, spodumene Name: Sodium Symbol: Na Atomic Number: 11 Atomic Mass: 22.98977 amu Melting Point: 97.8 °C (370.95 K, 208.04001 °F) Boiling Point: 552.9 °C (826.05005 K, 1027.2201 °F) Number of Protons/Electrons: 11 Number of Neutrons: 12 Classification: Alkali Metal Crystal Structure: Cubic
Density @ 293 K: 0.971 g/cm3 Color: silvery
Atomic Structure
Number of Energy Levels: 3 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 1
Isotopes Isotope Half Life Na-22
2.6 years
Na-23
Stable
Na-24
14.96 hours
Facts Date of Discovery: 1807 Discoverer: Sir Humphrey Davy Name Origin: soda (Na2CO3) Symbol Origin: From the Latin word natrium (sodium) Uses: medicine, agriculture Obtained From: table salts and other foods Name: Potassium Symbol: K Atomic Number: 19 Atomic Mass: 39.0983 amu Melting Point: 63.65 °C (336.8 K, 146.57 °F)
Boiling Point: 774.0 °C (1047.15 K, 1425.2 °F) Number of Protons/Electrons: 19 Number of Neutrons: 20 Classification: Alkali Metal Crystal Structure: Cubic Density @ 293 K: 0.862 g/cm3 Color: silvery
Atomic Structure
Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 8 Fourth Energy Level: 1
Isotopes Isotope Half Life K-39
Stable
K-40
1.28E9 years
K-41
Stable
K-42
12.4 hours
K-43
22.3 hours
Facts Date of Discovery: 1807 Discoverer: Sir Humphrey Davy Name Origin: potash
Symbol Origin: From the Latin word kalium Uses: glass, soap Obtained From: minerals (carnallite) Name: Rubidium Symbol: Rb Atomic Number: 37 Atomic Mass: 85.4678 amu Melting Point: 38.89 °C (312.04 K, 102.002 °F) Boiling Point: 688.0 °C (961.15 K, 1270.4 °F) Number of Protons/Electrons: 37 Number of Neutrons: 48 Classification: Alkali Metal Crystal Structure: Cubic Density @ 293 K: 1.532 g/cm3 Color: silver
Atomic Structure
Number of Energy Levels: 5 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 8 Fifth Energy Level: 1
Isotopes Isotope Half Life Rb-81
4.57 hours
Rb-82
2.25 minutes
Rb-83
86.2 days
Rb-84
32.9 days
Rb-85
Stable
Rb-86
18.65 days
Rb-87
4.8E10 years
Rb-88
17.7 minutes
Rb-89
15.44 minutes
Rb-90
2.6 minutes
Rb-90m 4.3 minutes
Facts Date of Discovery: 1861 Discoverer: R. Bunsen Name Origin: From the Latin word rubidus (red) Uses: catalyst, photocells Obtained From: lithium production Name: Cesium Symbol: Cs Atomic Number: 55 Atomic Mass: 132.90546 amu Melting Point: 28.5 °C (301.65 K, 83.3 °F) Boiling Point: 678.4 °C (951.55005 K, 1253.12 °F) Number of Protons/Electrons: 55 Number of Neutrons: 78 Classification: Alkali Metal Crystal Structure: Cubic Density @ 293 K: 1.873 g/cm3 Color: silver British Spelling: Caesium IUPAC Spelling: Caesium
Atomic Structure
Number of Energy Levels: 6 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 18 Fifth Energy Level: 8 Sixth Energy Level: 1
Isotopes Isotope Half Life Cs-126 1.6 minutes Cs-129 1.3 days Cs-131 9.7 days Cs-132 6.4 days Cs-133 Stable Cs-134 2.1 years Cs134m
2.9 hours
Cs-135
2300000.0 years
Cs-136 13.2 days Cs-137 30.2 years Cs-138 32.2 minutes Cs-139 9.3 minutes
Facts
Date of Discovery: 1860 Discoverer: Fustov Kirchoff Name Origin: From the Latin word caesius (sky blue) Uses: remosves air traces in vacuum tubes Obtained From: pollucite, lepidolite
ATOMS AND MOLECULES
Atoms Most of the Universe consists of matter and energy. Energy is the capacity to do work. Matter has mass and occupies space. All matter is composed of basic elements that cannot be broken down to substances with different chemical or physical properties. Elements are substances consisting of one type of atom, for example Carbon atoms make up diamond, and also graphite. Pure (24K) gold is composed of only one type of atom, gold atoms. Atoms are the smallest particle into which an element can be divided. The ancient Greek philosophers developed the concept of the atom, although they considered it the fundamental particle that could not be broken down. Since the work of Enrico Fermi and his colleagues, we now know that the atom is divisible, often releasing tremendous energies as in nuclear explosions or (in a controlled fashion in) thermonuclear power plants. Subatomic particles were discovered during the 1800s. For our purposes we will concentrate only on three of them. The proton is located in the center (or nucleus) of an atom, each atom has at least one proton. Protons have a charge of +1, and a mass of approximately 1 atomic mass unit (amu). Elements differ from each other in the number of protons they have, e.g. Hydrogen has 1 proton; Helium has 2. The neutron also is located in the atomic nucleus (except in Hydrogen). The neutron has no charge, and a mass of slightly over 1 amu. Some scientists propose the neutron is made up of a proton and electron-like particle. The electron is a very small particle located outside the nucleus. Because they move at speeds near the speed of light the precise location of electrons is hard to pin down. Electrons occupy orbitals, or areas where they have a high statistical probability of occurring. The charge on an electron is -1. Its mass is negligible (approximately 1800 electrons are needed to equal the mass of one proton). The atomic number is the number of protons an atom has. It is characteristic and unique for each element. The atomic mass (also referred to as the atomic
weight) is the number of protons and neutrons in an atom. Atoms of an element that have differing numbers of neutrons (but a constant atomic number) are termed isotopes. Isotopes can be used to determine the diet of ancient peoples by determining proportions of isotopes in mummified or fossilized human tissues. Biochemical pathways can be deciphered by using isotopic tracers. The age of fossils and artifacts can be determined by using radioactive isotopes, either directly on the fossil (if it is young enough) or on the rocks that surround the fossil 9for older fossils like dinosaurs). Isotopes are also the source of radiation used in medical diagnostic and treatment procedures.
Note that each of these isotopes of hydrogen has only one proton. Isotopes differ from each other in the number of neutrons, not in the number of protons. Some isotopes are radioisotopes, which spontaneously decay, releasing radioactivity. Other isotopes are stable. Examples of radioisotopes are Carbon14 (symbol 14C), and deuterium (also known as Hydrogen-2; 2H). Stable isotopes are 12C and 1H.
Carbon has three isotopes, of which carbon-12 and carbon-14 are the most well known.
The Periodic Table of the Elements. Each Roman numeraled column on the label (at least the ones ending in A) tells us how many electrons are in the outer shell of the atom. Each numbered row on the table tells us how many electron shells an atom has. Thus, Hydrogen, in column IA, row 1 has one electron in one shell. Phosphorous in column VA, row 3 has 5 electrons in its outer shell, and has three shells in total.
Electro ns and energy Electrons, because they move so fast (approximately at the speed of light), seem to straddle the fence separating energy from matter. Because of this, we think of electrons both as particles of matter (having mass is a property of matter) and as units (or quanta) of energy. When subjected to energy, electrons will acquire some of that energy.
Excitation of an electron by energy, causing the electron to "jump" to another electron (energy) level known as the excited state. An orbital is also an area of space in which an electron will be found 90% of the time. Orbitals are of different shapes. Each orbital has a characteristic energy state and a characteristic shape. The s orbital is spherical, and located closest to the nucleus. Since each orbital can hold a maximum of two electrons, atomic numbers above 2 must fill the other orbitals. The px, py, and pz orbitals are dumbbell shaped, along the x, y, and z axes respectively. The major energy levels (also known as shells) into which electrons fit, are (from the nucleus outward) K, L, M, and N. Sometimes these are numbered, with electron configurations being: 1s22s22p1, etc. This nomenclature tells us the 1st energy level (shell) has 2 electrons in the s orbital, and 2nd energy level has 2 electrons in its s orbital, plus one electron in its p orbital.
Geometry of orbitals. S-orbitals are spherical, p-orbitals are shaped like a dumbbell
Chemical Bonding During the nineteenth century, chemists arranged the then-known elements according to chemical bonding, recognizing that one group (the furthermost right column on the Periodic Table, referred to as the Inert Gases or Noble Gases) tended to occur in elemental form (in other words, not in a molecule with other elements). It was later determined that this group had outer electron shells containing two (as in the case of Helium) or eight (Neon, Xenon, Radon, Krypton, etc.) electrons. As a general rule, for the atoms we are likely to encounter in biological systems, atoms tend to gain or lose their outer electrons to achieve a Noble Gas outer electron shell configuration of 2 or 8 electrons. The number of electrons that are gained or lost is characteristic for each element, and ultimately determines the number and types of chemical bonds atoms of that element can form.
Atomic diagrams illustrating the filling of the outer electron shells. Ionic bonds are formed when atoms become ions by gaining or losing electrons. Chlorine is in a group of elements having seven electrons in their outer shells. Members of this group tend to gain one electron, acquiring a charge of -1. Sodium is in another group with elements having one electron in
their outer shells. Members of this group tend to lose that outer electron, acquiring a charge of +1. Oppositely charged ions are attracted to each other, thus Cl- (the symbolic representation of chlorine) and Na+ (the symbol for sodium, using the Greek word natrium) form an ionic bond, becoming the molecule sodium chloride. Ionic bonds generally form between elements in Group I (having one electron in their outer shell) and Group VIIa (having seven electrons in their outer shell). Such bonds are relatively weak, and tend to disassociate in water, producing solutions that have both Na and Cl ions.
Formation of a crystal of sodium chloride. Each positively charged sodium ion is surropunded by six negatively charged chloride ions; likewise each negatively charged chloride ion is surrounded by six positively charged sodium ions. The overall effect is electrical neutrality.
Table Salt Crystal (SEM x625). Covalent bonds form when atoms share electrons. Since electrons move very fast they can be shared, effectively filling or emptying the outer shells of the atoms involved in the bond. Such bonds are referred to as electron-sharing bonds. An analogy can be made to child custody: the children are like electrons, and tend to spend some time with one parent and the rest of their time with the other parent. In a covalent bond, the electron clouds surrounding the atomic nuclei overlap.
Formation of a covalent bond between two Hydrogen atoims. Carbon (C) is in Group IVa, meaning it has 4 electrons in its outer shell. Thus to become a "happy atom", Carbon can either gain or lose four electrons. By sharing the electrons with other atoms, Carbon can become a happy atom,. alternately filling and emptying its outer shell.
Formation of covalent bonds in methane. Carbon needs to share four electrons, in effect it has four slots. Each hydrogen provides an electron to each of these slots. At the same time each hydrogen needs to fill one slot, which is done by sharing an electron with the carbon.
The molecule methane (chemical formula CH4) has four covalent bonds, one between Carbon and each of the four Hydrogens. Carbon contributes an electron, and Hydrogen contributes an electron. The sharing of a single electron pair is termed a single bond. When two pairs of electrons are shared, a double bond results, as in carbon dioxide. Triple bonds are known, wherein three pairs (six electrons total) are shared as in acetylene gas or nitrogen gas.
Ways of representing covalent bonds. Sometimes electrons tend to spend more time with one atom than with another. In such cases a polar covalent bond develops. Water (H2O) is an example. Since the electrons spend so much time with the oxygen (oxygen having a greater electronegativity, or electron affinity) that end of the molecule acquires a slightly negative charge. Conversely, the loss of the electrons from the hydrogen end leaves a slightly positive charge. The water molecule is thus polar, having positive and negative sides. Hydrogen bonds result from the weak electrical attraction between the positive end of one molecule and the negative end of another. Individually these bonds are very weak, although taken in a large enough quantity, the result is strong enough to hold molecules together or in a three-dimensional shape.
Formation of a hydrogen bond between the hydrogen side of one water molecule and the oxygen side of another water molecule.
The presence of polar areas in the amino acids that makeup a protein allows for hydrogen bonds to form, giving the molecule a three-dimensional shape that is often vital to that protein's proper functioning.
Chemical reactions and molecules Molecule versus Mixture: Molecules are compounds with elements in definite, fixed ratios. Those atoms are held together usually by one of the three bonds discussed above. For example: water, glucose, ATP. Mixtures are compounds
with variable formulas/ratios of their components. For example: soil. Molecular formulas are an expression in the simplest whole-number terms of the composition of a substance. For example, the sugar glucose has 6 Carbons, 12 hydrogens, and 6 oxygens per repeating structural unit. The formula is written C6H12O6.
Determination of molecular weights by addition of the weights of the atoms that make up the molecule. Chemical reactions occur in nature, and somse also can be performed in a laboratory setting. Chemical Equations are linear representations of how these reactions occur. Combination reactions occur when two separate reactants are bonded together, e.g. A + B -----> AB. Disassociation reactions; occur when a compound is broken into two products, e.g. AB -----> A + B.
Diagram of a chemical reaction: the combustion of propane with oxygen, resulting in carbon dioxide, water, and energy (as heat and light). This chemical reaction takes place in a camping stove as well as in certain welding torches. Biological systems, while unique to each species, are based on the chemical bonding properties of carbon. Major organic chemicals (those associated with or formed by the actions of living things) usually include some ratios of the following elements: C, H, N, O, P, S.
Learning Objectives • • • • • •
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All forms of matter are composed of one or more elements. Be able to list the major elements in living things. Describe how protons, electrons, and neutrons are arranged into atoms and ions. Define the terms atomic number and atomic mass and be able to describe their sugnificance. Atoms with the same atomic number but a different mass number are isotopes. List the isotopes of hydrogen and of carbon. Be able to describe radioisotopes and list three ways they are used in biology. The union between the electron structures of atoms is known as the chemical bond. Be able to list and describe the three types of chemical bonds found in living things. Be able to describe the distribution of electrons in the space around the nucleus of an atom. An atom tends to react with other atoms when its outermost shell is only partly filled with electrons. Be able to discuss why this happens. Be able to define the two types of ions and describe thow ionic bonds form between positive and negative ions.
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In a covalent bond, atoms share electrons. List several elements that tend to form covalent bonds. Distinguish between a nonpolar covalent bond and a polar covalent bond and give an example of each. Define hydrogen bond and describe conditions under which hydrogen bonds form and cite one example. Explain what is meant by the polarity of the water molecule, and how the polarity of water molecules allows them to interact with one another.
WATER
Structure of Water It can be quite correctly argued that life exists on Earth because of the abundant liquid water. Other planets have water, but they either have it as a gas (Venus) or ice (Mars). Recent studies of mars reveal the presence sometime in the past of running fluid, possibly water. The chemical nature of water is thus one we must examine as it permeates living systems: water is a universal solvent, and can be too much of a good thing for some cells to deal with.
Water can exist in all three states of matter on Earth, while only in one state on our two nearest neighboring planets. Water is polar covalently bonded within the molecule. This unequal sharing of the electrons results in a slightly positive and a slightly negative side of the
molecule. Other molecules, such as Ethane, are nonpolar, having neither a positive nor a negative side.
The difference between a polar (water) and nonpolar (ethane) molecule is due to the unequal sharing of electrons within the polar molecule. Nonpolar molecules have electrons equally shared within their covalent bonds. Consequently, water has a great interconnectivity of individual molecules, which is caused by the individually weak hydrogen bonds that can be quite strong when taken by the billions.
Formation of a hydrogen bond between the hydrogen side of one water molecule and the oxygen side of another water molecule. Water has been referred to as the universal solvent. Living things are composed of atoms and molecules within aqueous solutions (solutions that have materials dissolved in water). Solutions are uniform mixtures of the molecules of two or more substances. The solvent is usually the substance present in the greatest amount (and is usually also a liquid). The substances of lesser amounts are the solutes.
Dissolution of an ionically bonded compound, sodium chloride, by water molecules. The solubility of many molecules is determined by their molecular structure. You are familiar with the phrase "mixing like oil and water." The biochemical basis for this phrase is that the organic macromolecules known as lipids (of which fats are an important, although often troublesome, group) have areas that lack polar covalent bonds. The polar covalently bonded water molecules act to exclude nonpolar molecules, causing the fats to clump together. The structure of many molecules can greatly influence their solubility. Sugars, such as glucose, have many hydroxyl (OH) groups, which tend to increase the solubility of the molecule.
Water tends to disassociate into H+ and OH- ions. In this disassociation, the oxygen retains the electrons and only one of the hydrogens, becoming a negatively charged ion known as hydroxide. Pure water has the same number (or concentration) of H+ as OH- ions. Acidic solutions have more H+ ions than OH- ions. Basic solutions have the opposite. An acid causes an increase in the numbers of H+ ions and a base causes an increase in the numbers of OH- ions.
pH of some common items. The pH scale is a logarithmic scale representing the concentration of H+ ions in a solution. Remember that as the H+ concentration increases the OHconcentration decreases and vice versa . If we have a solution with one in every ten molecules being H+, we refer to the concentration of H+ ions as 1/10. Remember from algebra that we can write a fraction as a negative exponent, thus 1/10 becomes 10-1. Conversely 1/100 becomes 10-2 , 1/1000 becomes 10-3, etc. Logarithms are exponents to which a number (usually 10) has been raised. For example log 10 (pronounced "the log of 10") = 1 (since 10 may be written as 101). The log 1/10 (or 10-1) = -1. pH, a measure of the concentration of H+
ions, is the negative log of the H+ ion concentration. If the pH of water is 7, then the concentration of H+ ions is 10-7, or 1/10,000,000. In the case of strong acids, such as hydrochloric acid (HCl), an acid secreted by the lining of your stomach, [H+] (the concentration of H+ ions, written in a chemical shorthand) is 10-1; therefore the pH is 1.
Organic molecules Organic molecules are those that: 1) formed by the actions of living things; and/or 2) have a carbon backbone. Methane (CH4) is an example of this. If we remove the H from one of the methane units below, and begin linking them up, while removing other H units, we begin to form an organic molecule. (NOTE: Not all methane is organically derived, methane is a major component of the atmosphere of Jupiter, which we think is devoid of life). When two methanes are combined, the resultant molecule is Ethane, which has a chemical formula C2H6. Molecules made up of H and C are known as hydrocarbons.
Types of hydrocarbon compounds and their structure. Scientists eventually realized that specific chemical properties were a result of the presence of particular functional groups. Functional groups are clusters of atoms with characteristic structure and functions. Polar molecules (with +/charges) are attracted to water molecules and are hydrophilic. Nonpolar molecules are repelled by water and do not dissolve in water; are hydrophobic. Hydrocarbon is hydrophobic except when it has an attached ionized functional group such as carboxyl (acid) (COOH), then molecule is hydrophilic. Since cells are 70-90% water, the degree to which organic molecules interact with water affects their function. One of the most common groups is the -OH (hydroxyl) group. Its presence will enable a molecule to be water soluble. Isomers are molecules with identical molecular formulas but differ in arrangement of their atoms (e.g., glyceraldehyde and dihydroxyacetone).
Functional groups in organic molecules. Carbon has four electrons in outer shell, and can bond with up to four other atoms (usually H, O, N, or another C). Since carbon can make covalent bonds with another carbon atom, carbon chains and rings that serve as the backbones of organic molecules are possible. Chemical bonds store energy. The C-C covalent bond has 83.1 Kcal (kilocalories) per mole, while the C=C double covalent bond has 147 Kcal/mole. Energy is in two forms: kinetic, or energy in use/motion; and potential, or energy at rest or in storage. Chemical bonds are potential energy, until they are converted into another form of energy, kinetic energy (according to the two laws of thermodynamics). Each organic molecule group has small molecules (monomers) that are linked to form a larger organic molecule (macromolecule). Monomers can be jouined together to form polymers that are the large macromolecules made of three to millions of monomer subunits. Macromolecules are constructed by covalently bonding monomers by condensation reactions where water is removed from functional groups on the monomers. Cellular enzymes carry out condensation (and the reversal of the reaction, hydrolysis of polymers). Condensation involves a dehydration synthesis because a water is removed (dehydration) and a bond is made (synthesis). When two monomers join, a hydroxyl (OH) group is removed from one monomer and a hydrogen (H) is removed from the other. This produces the water given off during a condensation reaction. Hydrolysis (hydration) reactions break down polymers in reverse of condensation; a hydroxyl (OH) group from water attaches to one monomer and hydrogen (H) attaches to the other. There are four classes of macromolecules (polysaccharides, triglycerides, polypeptides, nucleic acids). These classes perform a variety of functions in cells. 1. Carbohydrates have the general formula [CH2O]n where n is a number between 3 and 6. Note the different CH2O units on the diagram below.
Carbohydrates function in short-term energy storage (such as sugar); as intermediate-term energy storage (starch for plants and glycogen for animals); and as structural components in cells (cellulose in the cell walls of plants and many protists), and chitin in the exoskeleton of insects and other arthropods. Sugars are structurally the simplest carbohydrates. They are the structural unit which makes up the other types of carbohydrates. Monosaccharides are single (mono=one) sugars. Important monosaccharides include ribose (C5H10O5), glucose (C6H12O6), and fructose (same formula but different structure than glucose).
The chain (left) and ring (center and right) method of representing carbohydrates. Classification of monosaccharides is done by the number of carbon atoms and the types of functional groups. For example, glucose and fructose have the same chemical formula, but different structure: glucose having an aldehyde (internal hydroxyl shown as: -OH) and fructose having a keto group (internal double-bond O, shown as: =O).
Models of glucose and fructose. In aqueous solution, glucose tends to have two structures, α and β, with an intermediate straight-chain form. The α form and β form differ in the location of one -OH group. Glucose is a common hexose in plants. The products of photosynthesis are assembled to make a glucose. Energy from sunlight is converted into the C-C covalent bond energy. This energy is released in living organisms in such a way that not enough heat is generated at once to incinerate the organisms. One mole of glucose yields 673 Kcal of energy. (A calorie is the amount of heat needed to raise one gram of water one degree C. A Kcal has 1000 times as much energy as a cal.)
D-Glucose in various views (stick and space-filling) from the web. Disaccharides are formed when two monosaccharides are chemically bonded together. Sucrose, a common plant disaccharide is composed of the monosaccharides glucose and fructose. Lactose, milk sugar, is a disaccharide composed of glucose and the monosaccharide galactose.
Formation of a disaccharide (top) by condensation and structure of two common disaccharides. Polysaccharides are large molecules composed of individual monosaccharide units. A common plant polysaccharide is starch, which is made up of many glucoses (in a polypeptide these are referred to as glucans). Two forms of polysaccharide, amylose and amylopectin makeup what we commonly call starch. The formation of the ester bond by condensation (the removal of water from a molecule) allows the linking of monosaccharides into disaccharides and polysaccharides. Glycogen is an animal storage product that accumulates in the vertebrate liver.
Images of starch (top), glycogen (middle), and cellulose (bottom). Cellulose is a polysaccharide found in plant cell walls. Cellulose forms the fibrous part of the plant cell wall. In terms of human diets, cellulose is indigestible, and thus forms an important, easily obtained part of dietary fiber. As compared to starch and glycogen, which are each made up of mixtures of α and β glucoses, cellulose (and the animal structural polysaccharide chitin) are made up of only β glucoses. The three-dimensional structure of the structural polysaccharides is thus constrained into straight microfibrils by the uniform nature of the glucoses, which resist the actions of enzymes (such as amylase) that breakdown storage polysaccharides (such a starch).
Structure of cellulose as it occurs in a plant cell wall.
Cellulose Fibers from Print Paper (SEM x1,080). 2. Lipids are involved mainly with long-term energy storage. They are generally insoluble in polar substances such as water. Secondary functions of
lipids are as structural components (as in the case of phospholipids that are the major building block in cell membranes) and as "messengers" (hormones) that play roles in communications within and between cells. Lipids are composed of three fatty acids (usually) covalently bonded to a 3-carbon glycerol. The fatty acids are composed of CH2 units, and are hydrophobic/not water soluble.
Saturated (top and middle) and unsaturated (bottom) fatty acids. The term staurated refers to the "saturation" of the molecule by hydrogen atoms. The presence of a double C=C covalent bond reduces the number of hydrogens that can bond to the carbon chain, hence the application of therm "unsaturated". Fatty acids can be saturated (meaning they have as many hydrogens bonded to their carbons as possible) or unsaturated (with one or more double bonds connecting their carbons, hence fewer hydrogens). A fat is solid at room
temperature, while an oil is a liquid under the same conditions. The fatty acids in oils are mostly unsaturated, while those in fats are mostly saturated. Fats and oils function for in energy storage. Animals convert excess sugars (beyond their glycogen storage capacities) into fats. Most plants store excess sugars as starch, although some seeds and fruits have energy stored as oils (e.g. corn oil, peanut oil, palm oil, canola oil, and sunflower oil). Fats yield 9.3 Kcal/gm, while carbohydrates yield 3.79 Kcal/gm. Fats store six times as much energy as glycogen. Diets are attempts to reduce the amount of fats present in specialized cells known as adipose cells that accumulate in certain areas of the human body. By restricting the intakes of carbohydrates and fats, the body is forced to draw on its own stores to makeup the energy debt. The body responds to this by lowering its metabolic rate, often resulting in a drop of "energy level." Successful diets usually involve three things: decreasing the amounts of carbohydrates and fats; exercise; and behavior modification. Another use of fats is as insulators and cushions. The human body naturally accumulates some fats in the "posterior" area. Subdermal ("under the skin") fat plays a role in insulation. Phospholipids and glycolipids are important structural components of cell membranes. Phospholipids are modified so that a phosphate group (PO4-) is added to one of the fatty acids. The addition of this group makes a polar "head" and two nonpolar "tails". Waxes are an important structural component for many organisms, such as the cuticle, a waxy layer covering the leaves and stems of many land plants; and protective coverings on skin and fur of animals.
Structure of a phospholipid, space-filling model (left) and chain model (right). Cholesterol and steroids: Most mention of these two in the news is usually negative. Cholesterol has many biological uses, such as its occurrence in the cell membranes, and its role in forming the sheath of some neurons. Excess cholesterol in the blood has been linked to atherosclerosis, hardening of the arteries. Recent studies suggest a link between arterial plaque deposits of cholesterol, antibodies to the pneumonia-causing form of Chlamydia, and heart attacks. The plaque increases blood pressure, much the way blockages in plumbing cause burst pipes in old houses.
Structure of four steroids. 3. Proteins are very important in biological systems as control and structural elements. Control functions of proteins are carried out by enzymes and proteinaceous hormones. Enzymes are chemicals that act as organic catalysts (a catalyst is a chemical that promotes but is not changed by a chemical reaction). Click here for an illustrated page about enzymes. Structural proteins function in the cell membrane, muscle tissue, etc. The building block of any protein is the amino acid, which has an amino end (NH2) and a carboxyl end (COOH). The R indicates the variable component (R-group) of each amino acid. Alanine and Valine, for example, are both nonpolar amino acids, but they differ, as do all amino acids, by the composition of their R-groups. All living things (and even viruses) use various combinations of the same twenty amino acids. A very powerful bit of evidence for the phylogenetic connection of all living things.
Structure of an amino acid.
Structures in the R-groups of the twenty amino acids found in all living things. Amino acids are linked together by joining the amino end of one molecule to the carboxyl end of another. Removal of water allows formation of a type of covalent bond known as a peptide bond.
Formation of a peptide bond between two amino acids by the condensation (dehydration) of the amino end of one amino acid and the acid end of the other amino acid.
Amino acids are linked together into a polypeptide, the primary structure in the organization of proteins. The primary structure of a protein is the sequence of amino acids, which is directly related to the sequence of information in the RNA molecule, which in turn is a copy of the information in the DNA molecule. Changes in the primary structure can alter the proper functioning of the protein. Protein function is usually tied to their three-dimensional structure. The primary structure is the sequence of amino acids in a polypeptide.
Structure of a protein: primary, secondary, tertiary, and quaternary levels of structure.
The secondary structure is the tendency of the polypeptide to coil or pleat due to H-bonding between R-groups. The tertiary structure is controlled by bonding (or in some cases repulsion) between R-groups. Many proteins, such as hemoglobin, are formed from one or more polypeptides. Such structure is termed quaternary structure. Structural proteins, such as collagen, have regular repeated primary structures. Like the structural carbohydrates, the components determine the final shape and ultimately function. Collagens have a variety of functions in living things, such as the tendons, hide, and corneas of a cow. Keratin is another structural protein. It is found in fingernails, feathers, hair, and rhinoceros horns. Microtubules, important in cell division and structures of flagella and cilia (among other things), are composed of globular structural proteins.
4. Nucleic acids are polymers composed of monomer units known as nucleotides. There are a very few different types of nucleotides. The main functions of nucleotides are information storage (DNA), protein synthesis (RNA), and energy transfers (ATP and NAD). Nucleotides consist of a sugar, a nitrogenous base, and a phosphate. The sugars are either ribose or deoxyribose. They differ by the lack of one oxygen in deoxyribose. Both are pentoses usually in a ring form. There are five nitrogenous bases. Purines (Adenine and Guanine) are double-ring structures, while pyrimidines (Cytosine, Thymine and Uracil) are single-ringed.
Structure of two types of nucleotide. Deoxyribonucleic acid (better known as DNA) is the physical carrier of inheritance for 99% of living organisms. The bases in DNA are C, G, A and T. We will learn more about the DNA structure and function later in the course (click here for a quick look [actually take all the time you want!] ;)). DNA functions in information storage. The English alphabet has 26 letters and over 50,000 words. DNA has 4 letters (C, G, A, and T) and 20 words (the 20 amino acids) that can make an infinite variety of sentences (polypeptides).
Structure of a segment of a DNA double helix. Changes in information can alter the meaning of a sentence.
For example take the sentence: I saw Elvis. This implies certain knowledge (that I've been out in the sun too long without a hat, etc.). If we alter the sentence by inverting the middle word, we get: I was Elvis (thank you, thank you very much). Now we have greatly altered the information. A third alteration will change the meaning: I was Levis. Clearly the original sentence's meaning is now greatly changed. Changes in DNA information will be translated into changes in the primary structure of a polypeptide, and from there to the secondary and tertiary structures. A mutation is any change in the DNA base sequence. Most mutations are harmful, few are neutral, and a very few are beneficial and contribute the organism's reproductive success. Mutations are the wellspring of variation, variation is central to Darwin and Wallace's theory of evolution by natural selection. Ribonucleic acid (RNA) was discovered after DNA. DNA, with exceptions in chloroplasts and mitochondria, is restricted to the nucleus (in eukaryotes, the nucleoid region in prokaryotes). RNA occurs in the nucleus as well as in the cytoplasm (also remember that it occurs as part of the ribosomes that line the rough endoplasmic reticulum). There are three types of RNA: Messenger RNA (mRNA) is the blueprint for construction of a protein. Ribosomal RNA (rRNA) is the construction site where the protein is made. Transfer RNA (tRNA) is the truck delivering the proper amino acid to the site at the right time. Details of RNA and its role in protein synthesis are available by clicking here.
Structure a RNA molecule.
Learning Objectives •
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Dissolved substances are called solutes; a fluid in which one or more substances can dissolve is called a solvent. Describe several solutions that you use everyday in terms of what is the solvent and what is the solute. Define acid and base and be able to cite an example of each. The concentration of free hydrogen ions in solutions is measured by the pH scale.. Nearly all large biological molecules have theor organization influenced by interactions with water. Describe this interaction as it exists with carbohydrate molecules. Be able to list the three most abundant elements in living things. Each carbon atom can form as many as four covalent bonds with other carbon atoms as well as with other elements. Be able to explain why this is so. Be able to list the four main groups of organic molecules and their functions in living things. Enzymes are a special class of proteins that speed up chemical reactions in cells. What about the structure of proteins allows for the reaction specificity that occurs with most enzymes. Condensation reactions result in the formation of covalent bonds between small molecules to form larger organic molecules. Be able to describe a condensation reaction in words. Be able to describe what occurs during a hydrolysis reaction. Be able to define carbohydrates and list their functions.
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The simplest carbohydrates are sugar monomers, the monosaccharides. Be able to give examples and their functions. A polysaccharide is a straight or branched chain of hundreds or thousands of sugar monomers, of the same or different kinds. Be able to give common examples and their functions. Be able to define lipids and to list their functions. Distinguish betwen a saturated fat and an unsaturated fat. Why is such a distinction a life and death matter for many people? A phospholipid has two fatty acid tails attached to a glycerol backbone. What is the importance of these molecules. Define steroids and describe their chemical structure. Be able to discuss the importance of the steroids known as cholesterol and hormones. Be able to describe proteins and cite their general functions. Be prepared to make a sketch and name the three parts of every amino acid. o Describe the complex structure of a protein through its primary, secondary, tertiary, and quaternary structure. How does this relate to the three-dimensional structure of proteins? Describe the three parts of every nucleotide..
Chemistry Dictionary Absolute Entropy (of a substance) The increase in the entropy of a substance as it goes from a perfectly ordered crystalline form at 0 °K (where its entropy is zero) to the temperature in question. Absolute Zero The zero point on the absolute temperature scale; -273.15°C or 0 K; theoretically, the temperature at which molecular motion ceases. Absorption Spectrum Spectrum associated with absorption of electromagnetic radiation by atoms (or other species) resulting from transitions from lower to higher energy states. Accuracy How closely a measured value agrees with the correct value. Acid A substance that produces H+(aq) ions in aqueous solution. Strong acids ionize completely or almost completely in dilute aqueous solution. Weak acids ionize only slightly. Acid Anhydride The oxide of a nonmetal that reacts with water to form an acid. Acid Anhydride Compound produced by dehydration of a carbonic acid; general formula is R--C-O--C--R Acidic Salt A salt containing an ionizable hydrogen atom; does not necessarily produce acidic solutions. Activation Energy Amount of energy that must be absorbed by reactants in their ground states to reach the transition state so that a reaction can occur. Active Metal Metal with low ionization energy that loses electrons readily to form cations. Activity (of a component of ideal mixture) A dimensionless quantity whose magnitude is: equal to molar concentration in an ideal solution; equal to partial pressure in an ideal gas mixture; and defined as 1 for pure solids or liquids. Activity Series A listing of metals (and hydrogen) in order of decreasing activity Actual Yield Amount of a specified pure product actually obtained from a given reaction. Compare with Theoretical Yield. Actinides Elements 90 to 103 (after actinium) Acyl Group Compound derived from a carbonic acid by replacing the --OH group with a halogen (X), usually --Cl; general formula is O R--C--X Addition Reaction
A reaction in which two atoms or groups of atoms are added to a molecule, one on each side of a double or triple bond Adhesive Forces Forces of attraction between a liquid and another surface. Adsorption Adhesion of a species onto the surfaces of particles Alcohol Hydrocarbon derivative containing an --OH group attached to a carbon atom not in an aromatic ring. Aldehyde Compound in which an alkyl or aryl group and a hydrogen atom are attached to a carbonyl group and a hydrogen atom are attached to a carbonyl group; general formula, O-R-C-H Alkali Metals Metals of Group IA (Na, K, Rb). Alkaline Battery A dry cell in which the electrolyte contains KOH. Alkaline Earth Metals Group IIA metals Alkenes (Olefins) Unsaturated hydrocarbons that contain one or more carbon-carbon double bonds. Alkyl Group A group of atoms derived from an alkane by the removal of one hydrogen atom. Alkylbenzene A compound containing an alkyl group bonded to a benzene ring. Alkynes Unsaturated hydrocarbons that contain one or more carbon-carbon triple bonds. Allotropes Different forms of the same element in the same physical state. Allotropic Modifications (Allotropes) Different forms of the same element in the same physical state. Alloying Mixing of metal with other substances (usually other metals) to modify its properties. Alpha Particle A helium nucleus. Alpha (a) Particle Helium ion with 2+ charge; an assembly of two protons and two neutrons. Alums Hydrated sulfates of the general formula M+M3+(SO4)2.12H2). Amide Compound containing the O-C-N group. Compound that can be considered a derivative of ammonia in which one or more hydrogens are replaced by a alkyl or aryl groups. Amine
Derivatives of ammonia in which one or more hydrogen atoms have been replaced by organic groups. Amine Complexes Complex species that contain ammonia molecules bonded to metal ions. Amino Acid Compound containing both an amino and a carboxylic acid group.The --NH2 group. :Amino Acids Amorphous Solid A noncrystalline solid with no well-defined ordered structure. Ampere Unit of electrical current; one ampere equals one coulomb per second. Amphiprotism Ability of a substance to exhibit amphiprotism by accepting donated protons. Amphoterism The ability to react with both acids and bases. Ability of substance to act as either an acid or a base. Anion A negative ion; an atom or goup of atoms that has gained one or more electrons. Anode In a cathode ray tube, the positive electrode. Electrode at which oxidation occurs. Antibonding Orbital A molecular orbital higher in energy than any of the atomic orbitals from which it is derived; lends instability to a molecule or ion when populated with electrons; denoted with a star (*) superscript or symbol. Aromatic Hydrocarbons Benzene and its derivatives. Artificial Transmutation An artificially induced nuclear reaction caused by the bombardment of a nucleus with subatomic particiles or small nucei. Aryl Group Group of atoms remaining after a hydrogen atom is removed from the aromatic system. Associated Ions Short-lived species formed by the collision of dissolved ions of opposite charges. Atmosphere A unit of pressure; the pressure that will support a column of mercury 760 mm high at 0 °C. Atom The smallest particle of an element Atomic Mass Unit (amu) One twelfth of a mass of an atom of the carbon-12 isotope; a unit used for stating atomic and formula weights; also called dalton. Atomic Number Integral number of protons in the nucleus; defines the identity of element.
Atomic Orbital Region or volume in space in which the probability of finding electrons is highest. Atomic Radius Radius of an atom. Atomic Weight Weighted average of the masses of the constituent isotopes of an element; The relative masses of atoms of different elements. Aufbau ('building up') Principle Describes the order in which electrons fill orbitals in atoms. Autoionization An ionization reaction between identical molecules. Avogadro's Law At the same temperature and pressure, equal volumes of all gases contain the same number of molecules. Avogadro's Number The number (6.022x10^23) of atoms, molecules or particles found in exactly 1 mole of substance. Background Radiation Ratiation extraneous to an experiment. Usually the low-level natural radiation form cosmic rays and trace radioactive substances present in our environment. Band A series of very closely spaced, nearly continuous molecular orbitals that belong to the crystal as a whole. Band of Stability Band containing nonradioactive nuclides in a plot of number of neutrons versus atomic number. Band Theory of Metals Theory that accounts for the bonding and properties of metallic solids. Barometer A device for measuring pressure. Base A substance that produces OH (aq) ions in aqueous solution. Strong soluable bases are soluble in water and are completely dissociated. Weak bases ionize only slightly. Basic Anhydride The oxide of a metal that reacts with water to form a base. Basic Salt A salt containing an ionizable OH group. Beta Particle Electron emitted from the nucleus when a neuton decays to a proton and an electron. Biodegradability The ability of a substance to be broken down into simpler substances by bacteria. Binary Acid A binary compound in which H is bonded to one or more of the more electronegative nonmetals.
Binary Compound A compound consisting of two elements; may be ionic or covalent. Binding Energy (nuclear binding energy) The energy equivalent (E = mc^2) of the mass deficiency of an atom. where: E = is the energy in joules, m is the mass in kilograms, and c is the speed of light in m/s^2 Boiling Point The temperature at which the vapor pressure of a liquid is equal to the applied pressure; also the condensation point Boiling Point Elevation The increase in the boiling point of a solvent caused by the dissolution of a nonvolatile solute. Bomb Calorimeter A device used to measure the heat transfer between system and surroundings at constant volume. Analytical Chemistry Bond Energy The amount of energy necessary to break one mole of bonds of a given kind (in gas phase). The amount of energy necessary to break one mole of bonds in a substance, dissociating the sustance in the gaseous state into atoms of its elements in the gaseous state. Bond Order Half the numbers of electrons in bonding orbitals minus half the number of electrons in antibonding orbitals. Bonding Orbital A molecular orbit lower in energy than any of the atomic orbitals from which it is derived; lends stability to a molecule or ion when populated with electron Bonding Pair Pair of electrons involved in a covalent bond. Boron Hydrides Binary compounds of boron and hydrogen. Born-Haber Cycle A series of reactions (and accompanying enthalpy changes) which, when summed, represents the hypothetical one-step reaction by which elements in their standard states are converted into crystals of ionic compounds (and the accompanying enthalpy changes.) Boyle's Law At constant temperature the volume occupied by a definite mass of a gas is inversely proportional to the applied pressure. Breeder Reactor A nuclear reactor that produces more fissionable nuclear fuel than it consumes. Bronsted-Lowry Acid A proton donor. Bronsted-Lowry Base A proton acceptor
Buffer Solution Solution that resists change in pH; contains either a weak acid and a soluble ionic salt of the acid or a weak base and a soluble ionic salt of the base. Buret A piece of volumetric glassware, usually graduated in 0.1-mL intervals, that is used to deliver solutions to be used in titrations in a quantitative (dropwise) manner. Calorie The amount of heat required to raise the temperature of one gram of water from 14.5°C to 15.5°C. 1 calorie = 4.184 joules. Calorimeter A device used to measure the heat transfer between system and surroundings. Analytical Chemistry Canal Ray Stream of positively charged particles (cations) that moves toward the negative electrode in cathode ray tubes; observed to pass through canals in the negative electrode. Capillary A tube having a very small inside diameter. Capillary Action The drawing of a liquid up the inside of a small-bore tube when adhesive forces exceed cohesive forces, or the depression of the surface of the liquid when cohesive forces exceed the adhesive forces. Carbanion An organic ion carrying a negative charge on a carbon atom. Carbonium ion An orgainic ion carrying a positive charge on a carbon atom. Carcinogen A substance capable of causing or producing cancer in mammals. Catalyst A substance that speeds up a chemical reaction without being consumed itself in the reaction. A substance that alters (usually increases) the rate at which a reaction occurs. Catenation Bonding of atoms of the same element into chains or rings. The bonding together of atoms of the same element to form chains. The ability of an element to bond to itself. Cathode Electrode at which reduction occurs In a cathode ray tube, the negative electrode. Cathodic Protection Protection of a metal (making ir a cathode) against corrosion by attaching it to a sacrifical anode of a more easily oxidized metal. Cathode Ray Tube
Closed glass tube containing a gas under low pressure, with electrodes near the ends and a luminescent screen at the end near the positive electrode; produces cathode rays when high voltage is applied. Cation A positive ion; an atom or group of atoms that has lost one or more electrons. Cell Potential Potential difference, Ecell, between oxidation and reduction half-cells under nonstandard conditions. Central Atom An atom in a molecule or polyatomic ion that is bonded to more than one other atom. Chain Reaction A reaction that, once initiated, sustains itself and expands. This is a reaction in which reactive species, such as radicals, are produced in more than one step. These reactive species, radicals, propagate the chain reaction. Chain Termination Step The combination of two radicals, which removes the reactive species that propagate the change reaction. Charle's Law At constant pressure the volume occupied by a definite mass of gas is directly proportional to its absolute temperature. Chemical Bonds The attractive forces that hold atoms together in elements or compounds. Chemical Change A change in which one or more new substances are formed. Chemical Equation Description of a chemical reaction by placing the formulas of the reactants on the left and the formulas of products on the right of an arrow. Chemical Equilibrium A state of dynamic balance in which the rates of forward and reverse reactions are equal; there is no net change in concentrations of reactants or products while a system is at equilibrium. Chemical Hygiene Officer (CHO) A person or employee who is qualified by training or experience to provide technical guidance in the development and implementations of the provisions of a Chemical Hygiene Plan (CHP) Chemical Hygiene Plan (CHP) A written program developed and implemented by an employer designating proceedures, equipment, personal protective equipment, and work practices that are capable of protecting employees from the health hazards presented by hazardous chemicals usid in that particular workplace. Chemical Kinetics The study of rates and mechanisms of chemical reactions and of the factors on which they depend. Chemical Periodicity The variations in properties of elements with their position in the periodic table
CisThe prefix used to indicate that groups are located on the same side of a bon about which rotation is restricted. Cis-Trans Isomerism A type of geometrical isomerism related to the angles between like ligands. Clay A class of silicate and aluminosilicate minerals with sheet-like structures that have enormous surface areas that can absorb large amounts of water. Cloud Chamber A device for observing the paths of speeding particiles as vapor molecules condense on them to form foglike tracks. Coefficient of expansion The ratio of the change in length or volumen of a body to the original lengthor volume for a unit change in temperature. Cohesive Forces All the forces of attraction among particles of a liquid. Coke An impure form of carbon obtained by destructive distillation of coal or petroleum. Colligative Properties Physical properties of solutions that depend upon the number but not the kind of solute particles present. Collision Theory Theory of reaction rates that states that effective collisions between reactant molecules must occur in order for the reaction to occur. Colloid A heterogeneous mixture in which solute-like particles do not settle out. Combination Reaction Reaction in which two substances ( elements or compounds ) combine to form one compound. Reaction of a substance with oxygen in a highly exothermic reaction, usually with a visible flame. Combustible Classification of liquid substances that will burn on the basis of flash points. A combustible liquid means any liquid having a flash point at or above 37.8°C (100°F) but below 93.3°C (200°F), except any mixture having components with flash points of 93.3°C (200°F) or higher, the total of which makes up 99 percent or more of the total volume of the mixture. Common Ion Effect Suppression of ionization of a weak electrolyte by the presence in the same solution of a strong electrolyte containing one of the same ions as the weak electrolyte. Complex Ions Ions resulting from the formation of coordinate covalent bonds between simple ions and other ions or molecules. Composition Stoichiometry
Descibes the quantitative (mass) relationships among elements in compounds. Compound A substance of two or more elements in fixed proportions. Compounds can be decomposed into their constituent elements. Compounds Compressed Gas A gas or mixture of gases having, in a container an absolute pressure exceeding 40 psi at 21.1°C (70°F) A gass or mixture having in a container, an absolute pressure exceeding 104 psi at 54.4°C (130°F) regardless of the pressure at (21.1°C (70°F) A liquid having a vapour pressure exceeding 40 psi at 37.8°C (70°F) as determined by ASTM D-323-72. Concentration Amount of solute per unit volume or mass of solvent or of solution. Condensation Liquefaction of vapor. Condensed Phases The liquid and solid phases; phases in which particles interact strongly. Condensed States The solid and liquid states. Conduction Band A partially filled band or a band of vacant energy levels just higher in energy than a filled band; a band within which, or into which, electrons must be promoted to allow electrical conduction to occur in a solid. Conjugate Acid-base Pair In Bronsted-Lowry terminology, a reactant and product that differ by a proton, H+. Conformations Structures of a compound that differ by the extent of rotation about a single bond. Continuous Spectrum Spectrum that contains all wave-lengths in a specified region of the electromagnetic spectrum. Control Rods Rods of materials such as cadmium or boron steel that act as neutron obsorbers (not merely moderaters) used in nuclear reactors to control neutron fluxes and therfore rates of fission. Conjugated Double Bonds Double bonds that are separated from each other by one single bond -C=C-C=C-. Contact Process Industrial process by which sulfur trioxide and sulfuric acid are produced from sulfur dioxide. Coordinate Covalent Bond Covalent bond in which both shared electrons are furnished by the same species; bond between a Lewis acid and Lewis base. Coordinate Covalent Bond
A covalent bond in which both shared electrons are donated by the same atom; a bond between a Lewis base and a Lewis acid. Coordination Compound or Complex A compound containing coordinate covalent bonds. Coordination Isomers Isomers involving exchanges of ligands between complex cation and complex anion of the same compound. Coordination Number In describing crystals, the number of nearest neighbours of an atom or ion. The number of donor atoms coordinated to a metal. Coordination Sphere The metal ion and its coordinating ligands but not any uncoordinated counterions. Corrosion Oxidation of metals in the presence of air and moisture. Corrosion Coulomb Unit of electrical charge. Coulometry The quantitative application of Faraday's Law to the analysis of materials. The current and time are the usual variables measured. Covalent Bond Chemical bond formed by the sharing of one or more electron pairs between two atoms. Covalent Compounds Compounds containing predominantly covalent bonds. Critical Mass The minimum mass of a particular fissionable nuclide in a given volume required to sustain a nuclear chain reaction. Critical Point The combination of critical temperature and critical pressure of a substance. Critical Pressure The pressure required to liquefy a gas (vapor) at its critical temperature. Critical Temperature The temperature above which a gas cannot be liquefied; the temperature above which a substance cannot exhibit distinct gas and liquid phases. Crystal Field Stabilization Energy A measure of the net energy of stabilization gained by a metal ion's nonbonding d electrons as a result of complex formation. Crystallography Crystal Field Theory Theory of bonding in transition metal complexes in which ligands and metal ions are treated as point charges; a purely ionic model; ligand point charges represent the crystal (electrical) field perturbing the metal?s d orbitals containing nonbonding electrons. Crystal Lattice
A pattern of arrangement of particles in a crystal. Crystallography Crystal Lattice Energy Amount of energy that holds a crystal together; the energy change when a mole of solid is formed from its constituent molecules or ions (for ionic compounds) in their gaseous state. The energy charge when one mole of formula units of a crystalline solid is formed from its ions, atoms, or molecules in the gas phase; always negative. Crystallography Crystalline Solid A solid characterized by a regular, ordered arrangement of particles. Crystallography Curie (Ci) The basic unit used to describe the intensity of radioactivity in a sample of material. One curie equals 37 billion disintegrations per second or approximately the amount of radioactivty given off by 1 gram of radium. Cyclotron A device for accelerating charged particles along a spiral path. Daughter Nuclide Nuclide that is produced in a nuclear decay. Debye The unit used to express dipole moments. Degenerate Of the same energy. Delocalization Of electrons; refers to bonding electrons that are distributed among more than two atoms that are bonded together; occurs in species that exhibit resonance. The formation of a set of molecular orbitals that extend over more than two atoms; important in species that valence bond theory describes in terms of resonance. Denaturation A process pertaining to a change in structure of a protein form regular to irregular arrangement of the polypeptide chains. Denatured A commercial term used to describe ethanol that has been rendered unfit for human consumption because of the addition of harmful ingredients to make it sales tax-expempt. Density Mass per unit Volume: D=MV Deposition The direct solidification of a vapor by cooling; the reverse of sublimation. Derivative A compound that can be imagined to arise from a partent compound by replacement of one atom with another atom or group of atoms. Used extensively in orgainic chemistry to assist in identifying compounds. Dermal toxicity
Adverse health effects resulting from skin exposure ot a substance. Designated area An area that may be used for work with carcinogens, reproductive toxins, or substances that have a high degree of acute toxicity. A designated area may be the entire laboratory, an area of a laboratory, or a device such as a loboratory hood. Detergent A soap-like emulsifer that contains a sulfate, SO3 or a phosphate group instead of a carboxylate group. Deuterium An isotope of hydrogen whose atoms are twice as massive as ordinary hydrogen;deuterion atoms contain both a proton and a neutron in the nucleus. Dextrorotatory Refers to an optically active substance that rotates the plane of plane polarized light clockwise; also called dextro. Diagonal Similarities Refers to chemical similarities in the Periodic Table of elements of Period 2 to elements of Period 3 one group to the right; especially evident toward the left of the periodic table. Diamagnetism Weak repulsion by a magnetic field. Differential Scanning Calorimetry (DSC) A technique for measuring the temperature, direction, and magnitude of thermal transitions in a sample material by heating/cooling and comparing the amount of energy required to maintain its rate of temperature increase or decrease with an inert reference material under similar conditions. Differential Thermal Analysis (DTA) A technique for observing the temperature, direction, and magnitude of thermally induced transitions in a material by heating/cooling a sample and comparing its temperature with that of an inert reference material under similar conditions. Differential Thermometer A thermometer used for accurate measurement of very small changes in temperature. Dilution Process of reducing the concentration of a solute in solution, usually simply by mixing with more solvent. Dimer Molecule formed by combination of two smaller (identical) molecules. Dipole Refers to the separation of charge between two covalently bonded atoms Dipole-dipole Interactions Attractive interactions between polar molecules, that is, between molecules with permanent dipoles. Dipole Moment The product of the distance separating opposite charges of equal magnitude of the charge; a measure of the polarity of a bond or molecule; a measured dipole moment refers to the dipole moment of an entire molecule.
Dispersing Medium The solvent-like phase in a colloid. Dispersed Phase The solute-like species in a colloid. Displacement Reactions Reactions in which one element displaces another from a compound. Disproportionation Reactions Redox reactions in which the oxidizing agent and the reducing agent are the same species. Dissociation In aqueous solution, the process in which a solid ionic compound separates into its ions. Dissociation Constant Equilibrium constant that applies to the dissociation of a comples ion into a simple ion and coordinating species (ligands). Distilland The material in a distillation apparatus that is to be distilled. Distillate The material in a distillation apparatus that is collected in the receiver. Distillation The separation of a liquid mixture into its components on the basis of differences in boiling points. The process in which components of a mixture are separated by boiling away the more volitile liquid. Domain A cluster of atoms in a ferromagnetic substance, all of which align in the same direction in the presence of an external magnetic field. Donor Atom A ligand atom whose electrons are shared with a Lewis acid. D-Orbitals Beginning in the third energy level, aset of five degenerate orbitals per energy level, higher in energy than s and p orbitals of the same energy level. Dosimeter A small, calibrated electroscope worn by laboratory personnel and designated to detect and measure incident ionizing radiation or chemical exposure. Double Bond Covalent bond resulting from the sharing of four electrons (two pairs) between two atoms. Double Salt Solid consisting of two co-crystallized salts. Doublet Two peaks or bands of about equal intensity appearing close together on a spectrogram. Downs Cell Electrolytic cell for the commercial electrolysis of molten sodium chloride. DP number
The degree of polymerization; the average number of monomer units per polymer unit. Dry Cells Ordinary batteries (voltaic cells) for flashlights. radios, and so on; many are Leclanche cells. D -Transition elements (metals) B Group elements except IIB in the periodic table; sometimes called simply transition elements EX. Fe, Ni, Cu, Ti . Dumas Method A method used to determine the molecular weights of volatile liquids. Dynamic Equilibrium An equilibrium in which processes occur continuously, with no net change. When two (or more) processes occur at the same rate so that no net change occurs. Effective Collisons Collision between molecules resulting in a reaction; one in which the molecules collide with proper relative orientations and sufficient energy to react. Effective Molality The sum of the molalities of all solute particles in a solution. Effective Nuclear Charge The nuclear charge experienced by the outermost electrons of an atom; the actual nuclear charge minus the effects of shielding due to inner-shell electrons. Example: Set of dx2-y2 and dz2 orbitals; those d orbitals within a set with lobes directed along the x-, y-, and z-axes. Electrical Conductivity Ability to conduct electricity. Electrochemistry Study of chemical changes produced by electrical current and the production of electricity by chemical reactions. Electrodes Surfaces upon which oxidation and reduction half-reactions; occur in electrochemical cells. Electrode Potentials Potentials, E, of half-reactions as reductions versus the standard hydrogen electrode. Electrolysis Process that occurs in electrolytic cells. Electrolyte A substance whose aqueous solutions conduct electricity. Electrolytic Cells Electrochemical cells in which electrical energy causes nospontaneous redox reactions to occur. An electrochemical cell in which chemical reactions are forced to occur by the application of an outside source of electrical energy. Electrolytic Conduction
Conduction of electrical current by ions through a solution or pure liquid. Electromagnetic Radiation Energy that is propagated by means of electric and magnetic fields that oscillate in directions perpendicular to the direction of travel of the energy. Electromotive Series The relative order of tendencies for elements and their simple ions to act as oxidizing or reducing agents; also called the activity series. Electron A subatomic particle having a mass of 0.00054858 amu and a charge of 1-. Electron Affinity The amount of energy absorbed in the process in which an electron is added to a neutral isolated gaseous atom to form a gaseous ion with a 1- charge; has a negative value if energy is released. Electron Configuration Specific distribution of electrons in atomic orbitals of atoms or ions. Electron Deficient Compounds Compounds that contain at least one atom (other than H) that shares fewer than eight electrons Electronic Transition The transfer of an electron from one energy level to another. Electronegativity A measure of the relative tendency of an atom to attract electrons to itself when chemically combined with another atom. Electronic Geometry The geometric arrangement of orbitals containing the shared and unshared electron pairs surrounding the central atom of a molecule or polyatomic ion. Electrophile Positively charged or electron-deficient. Electrophoresis A technique for separation of ions by rate and direction of migration in an electric field. Electroplating Plating a metal onto a (cathodic) surface by electrolysis. Element A substance that cannot be decomposed into simpler substances by chemical means. Eluant or eluent The solvent used in the process of elution, as in liquid chromatography. Eluate Solvent (or mobile phase) which passes through a chromatographic column and removes the sample components from the stationary phase. Emission Spectrum Spectrum associated with emission of electromagnetic radiation by atoms (or other species) resulting from electronic transitions from higher to lower energy states. Emulsifying Agent
A sustance that coats the particles of the dispersed phase and prevents coagulation of colloidal particles; an emulsifier. Emulsion Colloidal suspension of a liquid in a liquid. Enantiomer One of the two mirror-image forms of an optically active molecule. Endothermic Describes processes that absorb heat energy. Endothermicity The absorption of heat by a system as the process occurs. End Point The point at which an indicator changes colour and a titration is stopped. Energy The capacity to do work or transfer heat. Enthalpy The heat content of a specific amount of substance; defined as E= PV. Entropy A thermodynamic state or property that measures the degree of disorder or randomness of a system. Enzyme A protein that acts as a catalyst in biological systems. Equation of State An equation that describes the behavior of matter in a given state; the van der Waals equation describes the behavior of the gaseous state. Equilibrium or Chemical Equilibrium A state of dynamic balance in which the rates of forward and reverse reactions are equal; the state of a system when neither forward or reverse reaction is thermodynamically favored. Equilibrium Constant A quantity that characterizes the position of equilibrium for a reversible reaction; its magnitude is equal to the mass action expression at equilibrium. K varies with temperature. Equivalence Point The point at which chemically equivalent amounts of reactants have reacted. Equivalent Weight An oxidizing or reducing agent, who's mass gains (oxidizing agents) or loses (reducing agents) 6.022 x 1023 electrons in a redox reaction. The mass of an acid or base that furnishes or reacts with 6.022 x 1023 H3O+ or OH- ions. Essential Oil A plant extract that has a distinctive odour or flavour. Ester A Compound of the general formula R-C-O-R1 where R and R1 may be the same or different, and may be either aliphatic or aromatic. Ether
Compound in which an oxygen atom is bonded to two alkyl or two aryl groups, or one alkyl and one aryl group. Eutrophication The undesirable overgrowth of vegetation caused by high concentrates of plant nutrients in bodies of water. Evaporization Vaporization of a liquid below its boiling point. Evaporation Rate The rate at which a particular substance will vapourize (evaporate) when compared to the rate of a known substance such as ethyl ether. This term is especially useful for health and fire-hazard considerations. Excited State Any state other than the ground state of an atom or molecule. Exothermic Describes processes that release heat energy. Exothermicity The release of heat by a system as a process occurs. Explosive A chemical or compound that causes a sudden, almost instantaneous release or pressure, gas, heat and light when subjected to sudden shock, pressure, high temperature or applied potential. Explosive limits The range of concentrations over which a flammable vapour mixed with proper ratios of air will ignite or explode if a source of ignitions is provided. Extensive Property A property that depends upon the amount of material in a sample. Extrapolate To estimate the value of a result outside the range of a series of known values. Technique used in standard additions calibration procedure. Faraday One faraday of electricity corresponds to the charge on 6.022 x 10 23 electrons, or 96,487 coulombs. Faraday's Law of Electrolysis One equivalent weight of a substance is produced at each electrode during the passage of 96,487 coulombs of charge through an electrolytic cell. Fast Neutron A neutron ejected at high kinetic energy in a nuclear reaction. Fat Solid triester of glycerol and (mostly) saturated fatty acids. Fatty Acids An aliphatic acid; many can obtained from animal fats. Ferromagnetism The ability of a substance to become permanently magnetized by exposure to an external magnetic field. Film badge
A small patch of photographic film worn on clothing to detect and measure accumulated incident ionizing radiation. Flammable A liquid as defined by NFPD and DOT as having a flash point below 37.8°C (100°F). Flash Point The temperature at which a liquid will yield enough flamable vapour to ignite. There are various recognized industrial testing methods; therefore the method used must be stated. Fluorescence Absorption of high energy radiation by a substance and subsequent emission of visible light. Fossil Fuels Substances consisting largely of hydrocarbons, derived from decay of organic materials under geological conditions of high pressure and temperature (metamorphism) include coal, petroleum, natural gas, peat and oil shale. Fuel Chemistry Frasch Process Method by which elemental sulfur is mined or extracted. Sulfur is melted with superheated water (at 170°C under high pressure) and forced to the surface of the earth as a slurry. First Law of Thermodynamics The total amount of energy in the universe is constant (also known as the Law of Conservation of Energy) energy is neither created nor destroyed in ordinary chemical reactions and physical changes. Thermochemistry Flotation Method by which hydrophobic (water-repelling) particles of an ore are separated from hydrophilic (water-attracting) particles of a metallurgical pretreatment process. Fluids Substances that flow freely; gases and liquids. Flotation Flux A substance added to react with the charge, or a product of its reduction, in metallurgy; usually added to lower a melting point. Foam Colloidal suspension of a gas in a liquid. Forbidden Zone A relatively large energy separation between an insulator's highest filled electron energy band and the next higher energy vacant band. Beginning in the fourth energy level, a set of seven degenerate orbitals per energy level, higher in energy than s, p, and d orbitals of the same energy level. Formal Charge A method of counting electrons in a covalently bonded molecule or ion; counts bonding electrons as though they were equally shared between the two atoms.
Formula Combination of symbols that indicates the chemical composition of a substance. Formula Unit The smallest repeating unit of a substance. The molecule for nonionic substances Formula Weight The mass of one formula unit of a substance in atomic mass units. Fractional Distillation The process in which a fractioning column is used in distillation apparatus to separate components of a liquid mixture that have different boiling points. Fractional Precipitation Removal of some ions from solution by precipitation while leaving other ions with similar properties in solution. Free Energy, Gibbs Free Energy The thermodynamic state function of a system that indicates the amount of energy available for the system to do useful work at constant T and P. Free Energy Change The indicator of spontaneity of a process at constnt T and P. If delta-G is negative, the process is spontaneous. Free Radical A highly reactive chemical species carrying no charge and having a single unpaired electron in an orbital. Freezing Point Depression The decrease in the freezing point of a solvent caused by the presence of a solute. Frequency The number of repeating corresponding points on a wave that pass a given observation point per unit time. Fuel Cells Voltaic cells in which the reactants (usually gases) are supplied continuously. A voltaic cell that converts the chemical energy of a fuel and an oxidizing agent directly into electriacl energy on a continuous basis. Functional Group A group of atoms that represents a potential reaction site in an organic compound. Gamma Ray High energy electromagnetic radiation. A highly penetrating type of nuclear radiation similar to x-ray radiation, except that it comes from within the nucleus of an atom and has a higher energy. Energywise, very similar to cosmic ray except that cosmic rays originate from outer space. Galvanizing Placing a thin layer of zinc on a ferrous material to protect the underlying surface from corrosion. Gangue Sand, rock, and other impurities surrounding the mineral of interest in an ore. Geiger counter A gas filled tube which discharges electriaclly when ionizing radiation passes through it.
Gel Colloidal suspension of a solid dispersed in a liquid; a semirigid solid. Gem-dimethyl group Two methyl groups of the same carbon atom. Geometrical Isomers Compounds with different arrangements of groups on either side of a bond with restricted rotation, such as a double bond or a single bond in a ring; for example cis-trans isomers of certain alkenes. Stereoisomers that are not mirror images of each other; also known as position isomers. Graham's Law The rates of effusion of gases are inversely proportional to the square roots of their molecular weights or densities. Greenhouse Effect Trapping of heat at the surface of the earth by carbon dioxide and water vapour in the atmosphere. Ground State The lowest energy state or most stable state of an atom, molecule or ion. Group A vertical column in the periodic table; also called a family. Haber Process A process for the catalyzed industrial production of ammonia from N2 and H2 at high temperature and pressure. Half-Cell Compartment in which the oxidation or reduction half-reaction occurs in a voltaic cell. Half-Life The time required for half of a reactant to be converted into product(s). The time required for half of a given sample to undergo radioactive decay. Half-Reaction Either the oxidation part or the reduction part of a redox reaction. Halogens Group VIIA elements: F, Cl, Br, I Hard Water Water containing Fe3+, Ca2+, and Mg2+ ions, which forms precipates with soap. Heat A form of energy that flows between two samples of matter because of their differences in temperature. Heat Capacity The amount of heat required to raise the temperature of a body (of any mass) one degree Celsius. Heat of Condensation The amount of heat that must be removed from one gram of a vapor at it's condensation point to condense the vapour with no change in temperature. Heat of Crystallization
The amount of heat that must be removed from one gram of a liquid at its freezing point to freeze it with no change in temperature. Heat of Fusion The amount of heat required to melt one gram of solid at its melting point with no change in temperature. Usually expressed in J/g. The molar heat of fusion is the amount of heat required to melt one mole of a solid at its melting point with no change in temperature and is usually expressed in kJ/mol. Heat of Solution The amount of heat absorbed in the formation of solution that contains one mole of solute; the value is positive if heat is absorbed (endothermic) and negative if heat is released (exothermic). Heat of Vaporization The amount of heat required to vaporize one gram of a liquid at its boiling point with no change in temperature. Usually expressed in J/g. The molar heat of vaporization is the amount of heat required to vaporize one mole of liquid at its boiling point with no change in temperature and usually expressed ion kJ/mol. Heavy Water Water containing deuterium, a heavy isotope of hydrogen. Heisenberg Uncertainty Principle It is impossible to determine accurately both the momentum and position of an electron simultaneously. Henry's Law The pressure of the gas above a solution is proportional to the concentration of the gas in the solution. Hess' Law of Heat Summation The enthalpy change for a reaction is the same whether it occurs in one step or a series of steps. Heterocyclic Amine Amine in which the nitrogen is part of a ring. Heterocyclic Chemistry Heterogeneous Catalyst A catalyst that exists in a different phase (solid, liquid or gas) from the reactants; a contact catalyst. Heterogeneous Equilibria Equilibria involving species in more than one phase. Heterogeneous Mixture A mixture that does not have uniform composition and properties throughout. Heteronuclear Consisting of different elements. High Spin Complex Crystal field designation for an outer orbital complex; all t2g and eg orbitals are singly occupied before any pairing occurs. Homogeneous Catalyst A catalyst that exists in the same phase (solid, liquid or gas) as the reactants. Catalysis Homogeneous Equilibria
Equilibria involving only one species in a single phase. For example, all gases, all liquids or all solids. Homogeneous Mixture A mixture which has uniform composition and properties throughout. Homologous Series A series of compounds in which each member differs from the next by a specific number and kind of atoms. Homonuclear Consisting of only one element. Hund's Rule All orbitals of a given sublevel must be occupied by single electrons before pairing begins (see Aufbau Principle) Hybridization Mixing a set of atomic orbitals to form a new set of atomic orbitals with the same total electron capacity and with properties and energies intermediate between those of the original unhybridized orbitals. Hydrate A solid compound that contains a definite percentage of bound water. Hydrate Isomers Isomers of crystalline complexes that differ in whether water is present inside or outside the coordination sphere Hydration Reaction of a substance with water. Hydration Energy The energy change accompanying the hydration of a mole of gase and ions. Hydride A binary compound of hydrogen. Hydrocarbons Compounds that contain only carbon and hydrogen. Hydrogen Bond A fairly strong dipole-dipole interaction (but still considerably weaker than the covalent or ionic bonds) between molecules containing hydrogen directly bonded to a small, highly electronegative atom, such as N, O, or F. Hydrogenation The reaction in which hydrogen adds across a double or triple bond. Hydrogen-Oxygen Fuel Cell Fuel cell in which hydrogen is the fuel (reducing agent) and oxygen is the oxidizing agent. Hydrolysis The reaction of a substance with water or its ions. Hydrolysis Constant An equilibrium constant for a hydrolysis reaction. Hydrometer A device used to measure the densities of liquids and solutions. Hydrophilic Colloids Colloidal particles that repel water molecules.
Inner Orbital Complex Valence bond designation for a complex in which the metal ion utilizes d orbitals for one shell inside the outermost occupied shell in its hybridization. Isomers Different substances that have the same formula. Ionization Isomers Isomers that result from the interchange of ions inside and outside the coordination sphere. Inert s-pair Effect Characteristic of the post-transition minerals; tendency of the outermost s electrons to remain nonionized or un shared in compounds. Insoluble Compound A very slightly soluble compound. Indicators For acid-base titrations, organic compounds that exhibit different colors in solutions of different acidities; used to determine the point at which reaction between two solutes is complete. Ionization Constant Equilibrium constant for the ionization of a weak electrolyte. Ion Product for Water Equilibrium constant for the ionization of water, Kw = [H3O+][OH-] =1.00 x 1014 at 25 °C. Inhibitory Catalyst An inhibitor, a catalyst that decreases the rate of reaction. Integrated Rate Equation An equation giving the concentration of a reactant remaining after a specified time; has different mathematical form for different orders of reactants. Ioniztion The breaking up of a compound into separate ions. Ideal Solution A solution that obeys Raoult's Law exactly. Insulator Poor electric and heat conductor. Intermolecular Forces Forces between individual particles (atoms, molecules, ions) of a substance. Isomorphous Refers to crystals having the same atomic arrangement. Ideal Gas A hypothetical gas that obeys exactly all postulates of the kinetic-molecular theory. Ideal Gas Law The product of pressure and the volume of an ideal gas is directly proportional to the number of moles of the gas and the absolute temperature. Ionization
In aqueous solution, the process in which a molecular compound reacts with water and forms ions. Ionic Bonding Chemical bonding resulting from the transfer of one or more electrons from one atom or a group of atoms to another. Ionic Compunds Compounds containing predominantly ionic bonding. Ionic Geometry The arrangement of atoms (not lone pairs of electrons) about the central atom of a polyatomic ion. Isoelectric Having the same electronic configurations Ionization Energy The minimum amount of energy required to remove the most loosely held electron of an isolated gaseous atom or ion. Isotopes Two or more forms of atoms of the same element with different masses; atoms containing the same number of protons but different numbers of neutrons. Ion An atom or a group of atoms that carries an electric charge. Joule A unit of energy in the SI system. One joule is 1 kg. m2/s2 which is also 0.2390 calorie K Capture Absorption of a K shell (n=1) electron by a proton as it is converted to a neutron. Ketone Compound in which a carbonyl group is bound to two alkyl or two aryl groups, or to one alkyl and one aryl group. Kinetic Energy Energy that matter processes by virtue of its motion. Kinetic-molecular Theory A theory, that attempts to explain macroscopic observations on gases in microscopic observations on gases in microscopic observations on gases in microscopic or molecular terms. Lanthanides Elements 58 to 71 (after lanthanum) Lanthanide Contraction A decrease in the radii of the elements following the lanthanides compared to what would be expected if there were no f-transition metals. Law of Combining Volumes (Gay-Lussac's Law) At constant temperature and pressure, the volumes of reacting gases ( and any gaseous products) can be expressed as ratios of small whole numbers; Law of Conservation of Energy Energy cannot be created or destroyed; it may be changed from one form to another. Law of Conservation of Matter
There is no detectable change in the quantity of matter during an ordinary chemical reaction. Law of Conservation of Matter and Energy The total amount of matter and energy available in the universe is fixed. Law of Definite Proportions (Law of Constant Composition) Different samples of a pure compound always contain the same elements in the same proportions by mass. Law of Partial Pressures (Dalton's Law) The total pressure exerted by a mixature of gases is the sum of the partial pressures of the individual gases. Lead Storage Battery Secondary voltaic cell used in most automobiles. Leclanche Cell A common type of dry cell. Le Chatelier's Principle States that a system at equilibrium, or striving to attain equilibrium, responds in such a way as to counteract any stress placed upon it. If a stress (change of conditions) is applied to a system at equilibrium, the system shifts in the direction that reduces stress. Leveling Effect Effect by which all acids stronger than the acid that is characteristic of the solvent react with solvent to produce that acid; similar statement applies to bases. The strongest acid (base) that can exist in a given solvent is the acid (base) characteristic of the solvent. Levorotatory Refers to an optically active substance that rotates the plane of plane polarized light counterclockwise; also called levo. Lewis Acid Any species that can accept a share in an electron pair. Lewis Base Any species that can make available a share in an electron pair. Lewis Dot Formula (Electron Dot Formula) Representation of a molecule, ion or formula unit by showing atomic symbols and only outer shell electrons Ligand A Lewis base in a coordination compound. Limiting Reactant Substance that stoichiometrically limits the amount of product(s) that can be formed. Linear Accelerator A device used for accelerating charged particles along a straight line path. Line Spectrum An atomic emission or absorption spectrum. Linkage Isomers Isomers in which a particular ligand bonds to a metal ion through different donor atoms.
Liquid Aerosol Colloidal suspension of liquid in gas. London Forces Very weak and very short-range attractive forces between short-lived temporary (induced) dipoles; also called dispersion Forces. Lone Pair Pair of electrons residing on one atom and not shared by other atoms; unshared pair. Low Spin Complex Crystal field designation for an inner orbital complex; contains electrons paired t2g orbitals before eg orbitals are occupied in octahedral complexes. Magnetic Quantum Number (mc) Quantum mechanical solution to a wave equation that designates the particular orbital within a given set (s, p, d, f ) in which a electron resides. Manometer A two-armed barometer. Mass A measure of the amount of matter in an object. Mass is usually measured in grams or kilograms. Mass Action Expression For a reversible reaction, aA + bB cC + dD the product of the concentrations of the products (species on the right), each raised to the power that corresponds to its coefficient in the balanced chemical equation, divided by the product of the concentrations of reactants (species on the left), each raised to the power that corresponds to its coefficient in the balanced chemical equation. At equilibrium the mass action expression is equal to K; at other times it is Q.[C]c[D]d [A]a[B]b = Q, or at equilibrium K Mass Deficiency The amount of matter that would be converted into energy if an atom were formed from constituent particles. Mass Number The sum of the numbers of protons and neutrons in an atom; an integer. Mass Spectrometer An instrument that measures the charge-to-mass ratio of charged particles. Matter Anything that has mass and occupies space. Mechanism The sequence of steps by which reactants are converted into products. Melting Point The temperature at which liquid and solid coexist in equilibrium; also the freezing point. Meniscus The shape assumed by the surface of a liquid in a cylindrical container. Metal An element below and to the left of the stepwise division (metalloids) in the upper right corner of the periodic table; about 80% of the known elements are metals.
Metallic Bonding Bonding within metals due to the electrical attraction of positively charges metal ions for mobile electrons that belong to the crystal as a whole. Metallic Conduction Conduction of electrical current through a metal or along a metallic surface. Metalloids Elements with properties intermediate between metals and nonmetals: B, Al, Si, Ge, As, Sb, Te, Po, and At. Metallurgy Refers to the overall processes by which metals are extracted from ores. Metathesis Reactions Reactions in which two compounds react to form two new compounds, with no changes in oxidation number. Reactions in which the ions of two compounds exchange partners. Method of Initial Rates Method of determining the rate-law expression by carrying out a reaction with different initial concentrations and analyzing the resultant changes in initial rates. Miscibility The ability of one liquid to mix with (dissolve in) another liquid. Mixture A sample of matter composed of two or more substances, each of which retains its identity and properties. Moderator A substance such as hydrogen, deuterium, oxygen or paraffin capable of slowing fast nuetrons upon collision. Molality Concentration expressed as number of moles of solute per kilogram of solvent. Molarity Number of moles of solute per litre of solution. Molar Solubility Number of moles of a solute that dissolve to produce a litre of saturated solution. Molecular Equation Equation for a chemical reaction in which all formulas are written as if all substances existed as molecules; only complete formulas are used. Molecular Formula Formula that indicates the actual number of atoms present in a molecule of a molecular substance. Molecular Geometry The arrangement of atoms (not lone pairs of electrons) around a central atom of a molecule or polyatomic ion. Molecular Orbital An orbit resulting from overlap and mixing of atomic orbitals on different atoms. An MO belongs to the molecule as a whole. Molecular Orbital Theory A theory of chemical bonding based upon the postulated existence of molecular orbitals.
Molecular Weight The mass of one molecule of a nonionic substance in atomic mass units. Molecule The smallest particle of an element or compound capable of a stable, independent existence. Mole Fraction The number of moles of a component of a mixture divided by the total number of moles in the mixture. Monoprotic Acid Acid that can form only one hydronium ion per molecule; may be strong or weak. Acid that contains one ionizable hydrogen atom per formula unit. Mother Nuclide Nuclide that undergoes nuclear decay. Native State Refers to the occurrence of an element in an uncombined or free state in nature. Natural Radioactivity Spontaneous decomposition of an atom. Nernst Equation Corrects standard electrode potentials for nonstandard conditions. Net Ionic Equation Equation that results from canceling spectator ions and eliminating brackets from a total ionic equation. Neutralization The reaction of an acid with a base to form a salt and water. Usually, the reaction of hydrogen ions with hydrogen ions to form water molecules. Neutron A neutral subatomic particle having a mass of 1.0087 amu. Nickel-cadmium cell (Nicad battery) A dry cell in which the anode is Cd, the cathode is NiO2, and the electrolyte is basic. Nitrogenases A class of enzymes found in bacteria within root nodules in some plants, which catalyze reactions by which N2 molecules from the air are converted to ammonia. Nitrogen Cycle The complex series of reactions by which nitrogen is slowly but continually recycled in the atmosphere, lithosphere and hydrosphere. Noble Gases (Rare Gases) Elements of the periodic Group 0; also called rare gases; formerly called inert gases, He,Ne,Ar, Kr, Xe, Rn. Nodal Plane A region in which the probability of finding an electron is zero. Nonbonding Orbital A molecular orbital derived only from an atomic orbital of one atom; lends neither stability nor instability to a molecule or ion when populated with electrons. Nonelectrolyte
A substance whose aqueous solutions do not conduct electricity. Nonpolar Bond Covalent bond in which electron density is symmetrically distributed Nuclear Binding Energy Energy equivalent of the mass deficiency; energy released in the formation of an atom from the subatomic particles. Nuclear Fission The process in which a heavy nucleus splits into nuclei of intermediate masses and one or more protons are emitted. Nuclear Reaction Involves a change in the composition of a nucleus and can evolve or absorb an extraordinarily large amount of energy Nuclear Reactor A system in which controlled nuclear fisson reactions generate heat energy on a large scale, which is subsequently converted into electrical energy. Nucleons Particles comprising the nucleus; protons and neutrons. Nucleus The very small, very dense, positively charged center of an atom containing protons and neutrons, as well as other subatomic particles. Nuclides Refers to different atomic forms of all elements in contrast to ?isotopes?, which refer only to different atomic forms of a single element. Nuclide Symbol Symbol for an atom A/Z E, in which E is the symbol of an element, Z is its atomic number, and A is its mass number. Octahedral A term used to describe molecules and polyatomic ions that have one atom in the center and six atoms at the corners of a octahedron. Octane Number A number that indicates how smoothly a gasoline burns. Octet Rule Many representative elements attain at least a share of eight electrons in their valence shells when they form molecular or ionic compounds; there are some limitations. Oil Liquid triester of glycerol and unsaturated fatty acids. Open Sextet Refers to species that have only six electrons in the highest energy level of the central element (many Lewis acids). Optical Activity The rotation of plane polarized light by one of a pair of optical isomers. Optical Isomers Stereoisomers that differ only by being nonsuperimposable mirror images of each other, like right and left hands, also called enantiomers. Ore
A natural deposit containing a mineral of an element to be extracted. Organic Chemistry The chemistry of substances that contain carbon-hydrogen bonds. Osmosis The process by which solvent molecules pass through a semipermable membrane from a dilute solution into a more concentrated solution. Osmotic Pressure The hydrostatic pressure produced on the surface of a semipermable membrane by osmosis. Ostwald Process A process for the industrial production of nitrogen oxide and nitric acid from ammonia and oxygen. Outer Orbital Complex Valence bond designation for a complex in which the metal ion utilizes d orbitals in the outermost (occupied) shell in hybridization. Overlap The interaction of orbitals on different atoms in the same region of space. Oxidation An algebraic increase in the oxidation number; may correspond to a loss of electrons. Oxidation Numbers Arbitrary numbers that can be used as mechanical aids in writing formulas and balancing equations; for single- atom ions they correspond to the charge on the ion; more electronegative atoms are assigned negative oxidation numbers (also called Oxidation states). Oxidation-reduction Reactions Reactions in which oxidation and reduction occur; also called redox reactions. Oxide A binary compound of oxygen. Oxidizing Agent The substance that oxidizes another substance and is reduced. Pairing A favourable interaction of two electrons with opposite m , values in the same orbital. Pairing Energy Energy required to pair two electrons in the same orbital. Paramagnetism Attraction toward a magnetic field, stronger than diamagnetism, but still weak compared to ferromagnetism. Partial Pressure The pressure exerted by one gas in a mixture of gases. Particulate Matter Fine divided solid particles suspended in polluted air. Pauli Exclusion Principle No two electrons in the same atom may have identical sets of four quantum numbers.
Percentage Ionization The percentage of the weak electrolyte that ionizes in a solution of given concentration. Percent by Mass 100% times the actual yield divided by theoretical yield. Percent Composition The mass percent of each element in a compound. Percent Purity The percent of a specified compound or element in an impure sample. Period The elements in a horizontal row of the periodic table. Periodicity Regular periodic variations of properties of elements with atomic number (and position in the periodic table). Periodic Law The properties of the elements are periodic functions of their atomic numbers. Periodic Table An arrangement of elements in order of increasing atomic numbers that also emphasizes periodicity. Peroxide A compound containing oxygen in the -1 oxidation state. Metal peroxides contain the peroxide ion, O22pH Negative logarithm of the concentration (mol/L) of the H3O+[H+] ion; scale is commonly used over a range 0 to 14. Phase Diagram Diagram that shows equilibrium temperature-pressure relationships for different phases of a substance. Phenol Hydrocarbon derivative containing an [OH] group bound to an aromatic raing. Photochemical Oxidants Photochemically produced oxidizing agents capable of causing damage to plants and animals. Photochemical Smog A brownish smog occurring in urban areas receiving large amounts of sunlight; caused by photochemical (light-induced) reactions among nitrogen oxides, hydrocarbons and other components of polluted air that produce photochemical oxidants. Photoelectric Effect Emission of an electron from the surface of a metal caused by impinging electromagnetic radiation of certain minimum energy; current increases with increasing intensity of radiation. Photon A packet of light or electromagnetic radiation; also called quantum of light Physical Change
A change in which a substance changes from one physical state to another but no substances with different composition are formed. Example Gas to Liquid - Solid. Plasma A physical state of matter which exists at extremely high temperatures in which all molecules are dissociated and most atoms are ionized. Polar Bond Covalent bond in which there is an unsymmetrical distribution of electron density. Polarimeter A device used to measure optical activity. Polarization The buildup of a product of oxidation or a reduction of an electrode, preventing further reaction. Polydentate Refers to ligands with more than one donor atom. Polyene A compound that contains more than one double bond per molecule. Polymerization The combination of many small molecules to form large molecules. Polymer A large molecule consisting of chains or rings of linked monomer units, usually characterized by high melting and boiling points. Polymorphous Refers to substances that crystallize in more than one crystalline arrangement. Polyprotic Acid An Acid that can form two or more hydronium ions per molecule; often a least one step of ionization is weak. Positron A Nuclear particle with the mass of an electron but opposite charge. Potential Energy Energy that matter possesses by virtue of its position, condition or composition. Precipitate An insoluble solid formed by mixing in solution the constituent ions of a slightly soluble solution. Primary Standard A substance of a known high degree of purity that undergoes one invariable reaction with the other reactant of interest. Primary Voltaic Cells Voltaic cells that cannot be recharged; no further chemical reaction is possible once the reactants are consumed. Proton A subatomic particle having a mass of 1.0073 amu and a charge of +1, found in thew nuclei of atoms. PseudobinaryIonic Compounds Compounds that contain more than two elements but are named like binary compounds. Quantum Mechanics
Mathematical method of treating particles on the basis of quantum theory, which assumes that energy (of small particles) is not infinitely divisible. Quantum Numbers Numbers that describe the energies of electrons in atoms; derived from quantum mechanical treatment. Radiation High energy particles or rays emitted during the nuclear decay processes. Radical An atom or group of atoms that contains one or more unpaired electrons (usually very reactive species) Radioactive Dating Method of dating ancient objects by determining the ratio of amounts of mother and daughter nuclides present in an object and relating the ratio to the object?s age via half-life calculations. Radioactive Tracer A small amount of radioisotope replacing a nonradioactive isotope of the element in a compound whose path (for example, in the body) or whose decomposition products are to be monitored by detection of radioctivity; also called a radioactive label. Radioactivity The spontaneous disintegration of atomic nuclei. Raoult's Law The vapor pressure of a solvent in an ideal solution decreases as its mole fraction decreases. Rate-determining Step The slowest step in a mechanism; the step that determines the overall rate of reaction. Rate-law Expression Equation relating the rate of a reaction to the concentrations of the reactants and the specific rate of the constant. Rate of Reaction Change in the concentration of a reactant or product per unit time. Reactants Substances consumed in a chemical reaction. Reaction Quotient The mass action expression under any set of conditions (not necessarily equlibrium); its magnitude relative to K determines the direction in which the reaction must occur to establish equilibrium. Reaction Ratio The relative amounts of reactants and products involved in a reaction; maybe the ratio of moles. millimoles, or masses. Reaction Stoichiometry Description of the quantitative relationships among substances as they participate in chemical reactions. Reducing Agent The substance that reduces another substance and is oxidized.
Resonance The concept in which two or more equivalent dot formulas for the same arrangement of atoms (resonance structures) are necessary to describe the bonding in a molecule or ion. Reverse Osmosis Forcing solvent molecules to flow through a semipermable membrane from a concentated solution into a dilute solution by the application of greater hydrostatic pressure on concentrated side than the osmotic pressure opposing it. Reversible Reaction Reactions that do not go to completion and occur in both the forward and reverse direction. Salt Bridge A U-shaped tube containing electrolyte, which connects two half-cells of a voltaic cell. Saponification Hydrolysis of esters in the presence of strong soluable bases. Saturated Hydrocarbons Hydrocarbons that contain only single bonds. They are also called alkanes or paraffin hydrocarbons. Saturated Solution Solution in which no more solute will dissolve. Second Law of Thermodynamics The universe tends toward a state of greater diorder in spontaneous processes. Secondary Standard a solution that has been titrated against a primary standard. A standard solution is a secondary standard. Secondary Voltaic Cells Voltaic cells that can be recharged; original reactanats can be regenerated be reversing the direction of the current flow. Semiconductor A substance that does not conduct electricity at low temperatures but does so at higher temperatures. Semipermable Membrane A thin partition between two solutions through which certain molecules can pass but others cannot. Shielding Effect Electrons in filled sets of s , p orbitals between the nucleus and outer shell electrons shield the outer shell electrons somewhat from the effect of protons in the nucleus; also called screening effect. Sigma Bonds Bonds resulting from the head-on overlap of atomic orbitals, in which the region of electron sharing is along and (cylindrically) symmetrical to the imaginary line connecting the bonded atoms. Sigma Orbital Molecular orbital resulting from head-on overlap of two atomic orbitals. Silicones
Polymeric organosilicon compounds; contain individual or cross-linked Si-O chains or rings in which some oxygens of SiO4 tetrahedra are replaced by other groups. Single Bond Covalent bond resulting from the sharing of two electrons (one pair) between two atoms. Solubility Product Constant Equilibrium constant that applies to the dissolution of a slightly soluble compound. Solubility Product Principle The solubility product constant expression for a slightly soluble compound is the product of the concentrations of the constituent ions, each raised to the power that corresponds to the number of ions in one formula unit. Solute The dispersed (dissolved) phase of a solution. Solution Homogeneous mixture of two or more substances. Solvation The process by which solvent molecules surround and interact with solute ions or molecules. Solvent The dispersing medium of a solution. Solvolysis The reaction of a substance with the solvent in which it is dissolved. S Orbital A spherically symmetrical atomic orbital; one per energy level. Specific Gravity The ratio of the density of a substance to the density of water. Specific Heat The amount of heat required to raise the temperature of one gram of substance one degree Celsius. Specific Rate Constant An experimentally determined (proportionality) constant, which is different for different reactions and which changes only with temperature; k in the rate-law expression: Rate = k [A] x [B]v. Spectator Ions Ions in a solution that do not participate in a chemical reaction. Spectral Line Any of a number of lines corresponding to definite wavelengths of an atomic emission or absorption spectrum; represents the energy difference between two energy levels. Spectrochemical Series Arrangement of ligands in order of increasing ligand field strength. Spectrum Display of component wavelengths (colours) of electromagnetic radiation. Square Planar
A term used to describe molecules and polyatomic ions that have one atom in the center and four atoms at the corners of a square. Square Planar Complex Complex in which the metal is in the center of a square plane, with ligand donor atoms at each of the four corners Standard Electrodes Half-cells in which the oxidized and reduced forms of a species are present at unit activity; 1.0M solutions of dissolved ions, 1.0atm partial pressure of gases, and pure solids and liquids. Standard Electrode Potential By convention , potential, Eo, of a half-reaction as a reduction relative to the standard hydrogen electrode when all species are present at unit activity. Standard Entropy The absolute entropy of a substance in its standard state at 298 K. Standard Molar Enthalphy of Formation The amount of heat absorbed in the formation of one mole of a substance in a specified state from its elements in their standard states. Standard Molar Volume The volume occupied by one mole of an ideal gas under standard conditions; 22.4liters. Standard Reaction A reaction in which the numbers of moles of reactants shown in the balanced equation, all in their standard states, are completely converted to the numbers of moles of products shown in the balanced equation, also sall at their standard state. Stereoisomers Isomers that differ only in the way that atoms are oriented in space; consist of geometrical and optical isomers. Stoichiometry Description of the quantitative relationships among elements and compounds as they undergo chemical changes. Strong Electrolyte A substance that conducts electricity well in a dilute aqueous solution. Strong Field Ligand Ligand that exerts a strong crystal or ligand electrical field and generally forms low spin complexes with metal ions when possible. Structural Isomers Compounds that contain the same number of the same kinds of atoms in different geometric arrangements. Sublimation The direct vaporization of a sold by heating without passing through the liquid state. Substance Any kind of matter all specimens of which have the same chemical composition and physical properties. Substitution Reaction
A reaction in which an atom or a group of atoms is replaced by another atom or group of atoms. Supercooled Liquids Liquids that, when cooled, apparently solidify but actually continue to flow very slowly under the influence of gravity. Supercritical Fluid A substance at temperature above its critical temperature. Supersaturated Solution A solution that contains a higher than saturation concentration of solute; slight disturbance or seeding causes crystallization of excess solute. Suspension A heterogeneous mixture in which solute-like particles settle out of solvent-like phase some time after their introduction. Temperature A measure of the intensity of heat, i.e. the hotness or coldness of a sample. or object. Ternary Acid A ternary compound containing H, O, and another element, often a nonmetal. Ternary Compound A compound consisting of three elements; may be ionic or covalent. Tetrahedral A term used to describe molecules and polyatomic ions that have one atom in center and four atoms at the corners of a tetrahedron. Theoretical Yield Maximum amount of a specified product that could be obtained from specified amounts of reactants, assuming complete consumption of limiting reactant according to only one reaction and complete recovery of product. (Compare with Actual Yield) Thermal Cracking Decomposition by heating a substance in the presence of a catalyst and in the absence of air. Thermodynamics The study of the energy transfers accompanying physical and chemical processes. Thermonuclear Energy Energy from nuclear fusion reactions. Third Law of Thermodynamics The entropy of a hypothetical pure, perfect, crystalline sustance at absolute zero temperature is zero. Titration A Procedure in which one solution is added to another solution until the chemical reaction between the two solutes is complete; the concentration of one solution is known and that of the other is unknown. Total Ionic Equation Equation for a chemical reaction written to show the predominant form of all species in aqueous solution or in contact with water. Transition State Theory
Theory of reaction rates that states that reactants pass through high-energy transition states before forming products. Tyndall Effect The scattering of light by colloidal particles. Unsaturated Hydrocarbons Hydrocarbons that contain double or triple carbon-carbon bonds Valence Bond Theory Assumes that covalent bonds are formed when atomic orbitals on different atoms overlap and the electrons are shared. Valence Electrons Outermost electrons of atoms; usually those involved in bonding. Valence Shell Electron Pair Repulsion Theory Assumes that electron pairs are arranged around the central element of a molecule or polyatomic ion so that there is maximum separation (and minimum repulsion) among regions of high electron density. van der Waals' Equation An equation of state that extends the ideal gas law to real gases by inclusion of two empirically determined parameters, which are different for different gases. Vapor A gas formed by boiling or evaporating a liquid. Vapor Pressure The particle pressure of a vapor at the surface of its parent liquid. Voltage Potential difference between two electrodes; a measure of the chemical potential for a redox reaction to occur. Voltaic Cells Electrochemical cells in which spontaneous chemical reactions produce electricity; also called galvanic cells. Water Equivalent The amount of water that would absorb the same amount of heat as the calorimeter per degree temperature increase. Weak Electrolyte A substance that conducts electricity poorly in a dilute aqueous solution. Weak Field Ligand A Ligand that exerts a weak crystal or ligand field and ge- nerally forms high spin complexes with metals. Zone Refining A method of purifying a bar of metal by passing it through an induction heater; this causes impurties to move along a melted portion.
