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The radii of atoms and ions are defied by the maximum radial charge densities of their outermost electron shells. Their sizes vary and are difficult to quantify and measure.
Table 3131. Periodic table for ionic radii (pm) of chemical elements (Atomic Radius = AR, Covalent Radius = 0, positively and negatively charged Ionic Radius = +/-, High Spin = HS, Low Spin = LS, Square Planar = SQ, and Coordination Number 2 = CN2; … Coordination Number 14 = CN14 for the ions with the same charges).
| 1 |
2 |
|
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
| |
1 H
Hydrogen
AR = 79
0 = 32
-1 = 154
|
|
2 He
Helium
AR = 128
|
| |
3 Li
Lithium
AR = 152
0 = 163
+1 = 78: [CN4=73; CN6=90; CN8=106]
|
4 Be
Beryllium
AR = 111
0 = 90
+2 = 31: [CN4=41; CN6=59]
|
|
5 B
Boron
AR = 98
0 = 82
+3 = 23: [CN4=23]
|
6 C
Carbon
AR = 91
0 = 77
+4 = 16: [CN4=29]
-4 = 260
|
7 N
Nitrogen
AR = 92
0 = 75
+5 = 13
-3 = 171: [CN4=132]
|
8 O
Oxygen
AR = 73
0 = 73
-2 = 140: [CN2=121; CN4=124; CN6=126; CN8=128] |
9 F
Fluorine
AR = 64
0 = 72
-1 = 133: [CN2=115; CN4=117; CN6=119]
|
10 Ne
Neon
AR = 38
0 = 71
|
| |
|
11 Na
Sodium
AR = 186
0 = 154
+1 = 95:[CN4=113; CN6=116; CN8=132; CN12=153]
|
12 Mg
Magnesium
AR = 160
0 = 136
+2 = 66: [CN4=71; CN6=86; CN8=103]
|
13 Al
Aluminium
AR = 143
0 = 118
+3 = 50: [CN4=53; CN6=68]
|
14 Si
Silicon
AR = 132
0 = 111
+4 = 41: [CN4=40; CN6=54]
-4 = 271
|
15 P
Phosphorus
AR = 128
0 = 106
+3 = 58: [CN6=58]
+5 = 35: [CN4=17; CN6=38]
-3 = 212
|
16 S
Sulphur
AR = 104
0 = 102
+6 = 30: [CN4=12; CN6=29]
-2 = 184: [CN4=184; CN6=190]
|
17 Cl
Chlorine
AR = 99
0 = 99
-1 = 181: [CN6=167]
|
18 Ar
Argon
AR = 71
0 = 98
|
| |
19 K
Potassium
AR = 235
0 = 203
+1 = 133: [CN4=151; CN6=152; CN8=165; CN10=173; CN12=178]
|
20 Ca
Calcium
AR = 197
0 = 174
+2 = 99: [CN6=114; CN8=126; CN10=137; CN12=148]
|
|
21 Sc
Scandium
AR = 162
0 = 144
+2 = 81
+3 = 88.5: [CN6=89; CN8=101]
|
22 Ti
Titanium
AR = 147
0 = 132
+2 = 91: [CN6=100]
+3 = 76: [CN6=81]
+4 = 74.5: [CN4=56; CN6=75; CN8=88] |
23 V
Vanadium
AR = 134
0 = 122
+2 = 88: [CN6=75]
+3 = 74: [CN6=78]
+4 = 72
+5 = 68
|
24 Cr
Chromium
AR = 130
0 = 118
+2 = 84: [HS:CN6=94] [LS:CN6=87]
+3 = 69: [CN6=76]
+4 = 68
+5 = 63
+6 = 58
|
25 Mn
Manganese
AR = 135
0 = 117
+2 = 80: [HS:CN4=80; HS:CN6=97; LS: CN6=81]
+3 = 66: [HS: CN6=79; LS: CN6=72]
+7 = 60 |
26 Fe
Iron
AR = 126
0 = 117
+2 = 76: [HS:CN4=77; HS:CN6=92; LS:CN6=75]
+3 = 64: [HS:CN4=63; HS:CN6=79; LS:CN6=69]
|
27 Co
Cobalt
AR = 125
0 = 116
+2 = 76: [HS:CN4=72; HS:CN6=89; LS:CN6=79]
+3 = 63: [HS:CN6=75; LS:CN6=69]
|
28 Ni
Nickel
AR = 124
0 = 115
+2 = 72: [CN4=69; CN6=83; SQ:CN4=63]
+3: [HS:CN6=74; LS:CN6=70]
|
29 Cu
Copper
AR = 128
0 = 117
+1 = 91: [CN2=60; CN4=74; CN6=91]
+2 = 69: [CN4=71; CN6=87]
|
30 Zn
Zinc
AR = 138
0 = 125
+2 = 74: [CN4=74; CN6=88; CN8=104]
|
31 Ga
Gallium
AR = 141
0 = 126
+1 = 81
+3 = 62: [CN4=61; CN6=76]
|
32 Ge
Germanium
AR = 137
0 = 122
+2 = 73
+4 = 53: [CN4=53; CN6=67]
|
33 As
Arsenic
AR = 139
0 = 120
+5 = 46: [CN4=48; CN6=60]
-3 = 222: [CN6=72]
|
34 Se
Selenium
AR = 117
0 = 116
+6 = 42
-2 = 198: [CN6=184]
|
35 Br
Bromine
AR = 114
0 = 114
+5 = 47
-1 = 196: [CN6=182]
|
36 Kr
Krypton
AR = 88
0 = 112
|
| |
37 Rb
Rubidium
AR = 248
0 = 216
+1 = 148: [CN6=166; CN8=175; CN10=180; CN12=186; CN14=197]
|
38 Sr
Strontium
AR = 215
0 = 191
+2 = 112: [CN6=132; CN8=140; CN10=150; CN12=158]
|
|
39 Y
Yttrium
AR = 178
0 = 162
+3 = 104: [CN6=104]
|
40 Zr
Zirconium
AR = 160
0 = 145
+4 = 86: [CN4=73; CN6=86; CN8=98]
|
41 Nb
Niobium
AR = 146
0 = 134
+3 = 86: [CN6=86]
+4 = 82: [CN6=82; CN8=93]
+5 = 78
|
42 Mo
Molybdenum
AR = 139
0 = 130
+3 = 83: [CN6=83]
+4 = 79: [CN6=79]
+5 = 75
+6 = 73
|
43 Tc
Technetium
AR = 136
0 = 127
+4 = 78.5: [CN6=79]
+5 = 74
+7 = 70
|
44 Ru
Ruthenium
AR = 134
0 = 125
+3 = 82: [CN6=82]
+4 = 76: [CN6=76]
+5 = 70.5
|
45 Rh
Rhodium
AR = 134
0 = 125
+3 = 80.5: [CN6=81]
+4 = 74: [CN6=74]
+5 = 69
|
46 Pd
Palladium
AR = 137
0 = 128
+2 = 100: [SQ:CN4=78; CN6=100]
+3 = 90
+4 = 75.5
|
47 Ag
Silver
AR = 144
0 = 134
+1 = 129: [CN2=81; CN4=114; SQ:CN4=116; CN6=129; CN8=142]
+2 = 108
+3 = 89 |
48 Cd
Cadmium
AR = 154
0 = 148
+2 = 109: [CN4=92; CN6=109; CN8=124; CN12=145]
|
49 In
Indium
AR = 166
0 = 144
+3 = 81: [CN4=76; CN6=94; CN8=106]
|
50 Sn
Tin
AR = 162
0 = 141
+2 = 93
+4 = 71: [CN4=69; CN6=83; CN8=95]
|
51 Sb
Antimony
AR = 159
0 = 140
+3: [CN6=90]
+6 = 62
-3 = 245
|
52 Te
Tellurium
AR = 143
0 = 136
+6 = 56
-2 = 221: [CN6=207]
|
53 I
Iodine
AR = 133
0 = 133
+7 = 50
-1 = 220: [CN6=206]
|
54 Xe
Xenon
AR = 108
0 = 131
|
| |
55 Cs
Cesium
AR = 267
0 = 235
+1 = 170: [CN6=181; CN8=188; CN10=195; CN12=202]
|
56 Ba
Barium
AR = 222
0 = 198
+2 = 134: [CN6=149; CN8=156; CN10=166; CN12=175]
|
{57-70}
Lanthanoid |
71 Lu
Lutetium
AR = 175
0 = 156
+3 = 85: [CN6=100; CN8=112]
|
72 Hf
Hafnium
AR = 167
0 = 144
+3 = 90
+4 = 85: [CN4=72; CN6=85; CN8=97]
|
73 Ta
Tantalum
AR = 149
0 = 134
+3 = 86: [CN6=86]
+4 = 82: [CN6=82]
+5 = 78
|
74 W
Tungsten
AR = 141
0 = 130
+4 = 80: [CN6=80]
+5 = 76
+6 = 74
|
75 Re
Rhenium
AR = 137
0 = 128
+4 = 77: [CN6=77]
+5 = 72
+6 = 69
+7 = 67
|
76 Os
Osmium
AR = 135
0 = 126
+4 = 77: [CN6=77]
+5 = 71.5
+6 = 69
|
77 Ir
Iridium
AR = 136
0 = 127
+3 = 82: [CN6=82]
+4 = 76.5: [CN6=77]
+5 = 71
|
78 Pt
Platinum
AR = 139
0 = 130
+2 = 94: [SQ:CN4=74; CN6=94]
+4 = 76.5: [CN6=77]
+5 = 71
|
79 Au
Gold
AR = 146
0 = 134
+1 = 51: [CN6=151]
+3 = 99: [SQ:CN4=82; CN6=99]
+5 = 71
|
80 Hg
Mercury
AR = 157
0 = 149
+1 = 133
+2 = 116: [CN2=83; CN4=110; CN6=116; CN8=128]
|
81 Tl
Thallium
AR = 171
0 = 148
+1 = 147
+3 = 95: [CN4=89; CN6=103; CN8=112]
|
82 Pb
Lead
AR = 175
0 = 147
+2 = 120: [CN4=112; CN6=133; CN8=143; CN10=154; CN12=163]
+4 = 84:
[CN4=79; CN6=92; CN8=108]
|
83 Bi
Bismuth
AR = 170
0 = 146
+3 = 96: [CN6=117; CN8=131]
+5 = 74
|
84 Po
Polonium
AR = 176
0 = 146
+4: [CN6=108; CN8=122]
+6 = 67
|
85 At
Astatine
AR = 127
0 = 145
+7 = 62: [CN6=76]
|
86 Rn
Radon
AR = 120
|
| |
87 Fr
Francium
+1 = 180: [CN6=194]
|
88 Ra
Radium
+2 = 143: [CN8=162; CN12=184]
|
[89-102]
Actinoid |
103 Lr
Lawrencium
|
104 Rf
|
105 Db
|
106 Sg
|
107 Bh
|
108 Hs
|
109 Mt
|
110 Ds
|
111 Uuu
|
112 Uub
|
|
114 Uuq
|
| |
| {lanthanides} {57-70} |
57 La
Lanthanum
AR = 187
0 = 169
+3 = 117.2: [CN6=117; CN8=130; CN10=141; CN12=150]
|
58 Ce
Cerium
AR = 181
0 = 165
+3 = 103: [CN6=115;
CN8=128;
CN10=139;
CN12=148]
+4 = 92
|
59 Pr
Praseodymium
AR = 182
0 = 165
+3 = 101: [CN6= 113; CN8=127]
+4 = 90
|
60 Nd
Neodymium
AR = 182
0 = 184
+3 = 100: [CN6=112; CN8=125; CN12=141]
|
61 Pm
Prometium
AR = 205
0 = 163
+3 = 97: [CN6=111; CN8=123]
|
62 Sm
Samarium
AR = 181
0 = 162
+3 = 96: [CN6=110; CN8=122; CN12=138]
|
63 Eu
Europium
AR = 199
0 = 185
+2 = 95
+3 = 120.6: [CN6=109; CN8=121]
|
64 Gd
Gadolinium
AR = 179
0 = 161
+3 = 94: [CN6=108; CN8=119]
|
65 Tb
Terbium
AR = 180
0 = 159
+3 = 92: [CN6=106; CN8=118]
+4 = 84
|
66 Dy
Dysprosium
AR = 180
0 = 159
+3 = 91: [CN6=105; CN8=117]
|
67 Ho
Holmium
AR = 179
0 = 158
+3 = 90: [CN6=104; CN8=116; CN10=126]
|
68 Er
Erbium
AR = 178
0 = 157
+3 = 89: [CN6=103; CN8=114]
|
69 Th
Thulium
AR = 177
0 = 156
+3 = 87: [CN6=102; CN8=113]
|
70 Yb
Ytterbium
AR = 194
+2 = 93
+3 = 112: [CN6=101; CN8=113]
|
|
| |
| {actinides} [89-102] |
89 Ac
Actinium
AR = 188
+3 = 118: [CN6=126]
|
90 Th
Thorium
AR = 180
0 = 165
+4 = 102: [CN6=108; CN8=119; CN10=127; CN12=135]
|
91 Pa
Protactinium
AR = 161
+3 = 113
+5 = 89
|
92 U
Uranium
AR = 138
0 = 142
+4 = 97
+6 = 80
|
93 Np
Neptunium
AR = 130
+3 = 110
+4 = 95
|
94 Pu
Plutonium
AR = 151
+3 = 108
+4 = 93
|
95 Am
Americium
AR = 173
+3 = 107
+4 = 92
|
96 Cm
Curium
AR = 299
|
97 Bk
Berkelium
AR = 297
|
98 Cf
Californium
AR = 295
|
99 Es
Einsteinium
AR = 292
|
100 Fm
Fermium
AR = 290
|
101 Md
Mendelevium
AR = 287
|
102 No
Nobelium
AR = 285
|
|
* The common ionic states are in green.
The size of an atom or ion depends on the size of the nucleus as well as the number of electrons. In general, atoms with more electrons have larger radii than those with fewer electrons.
The magnitude of ionic radii in the ionic crystals is mainly influenced by the following factors:
i) Coordination number.
The coordination number is defined as the number of atoms that surround a particular atom or ion in the structure. With the increase of coordination number, the inter-ionic distance and thus the ionic radius increase because each ion with a greater coordination number is surrounded by a greater number of ions and thus results in less attraction between the ions.
ii) Radius ratio.
Radius ratio influences the magnitude of ionic radii.
iii) Covalent character.
Covalent character in the ionic bond existing between the cation and anion decreases the inter-ionic distance, resulting in a smaller ionic radius.
Figure 3131. Ionic radii of 3d elements.
