Atomic radii of the elements (data page)

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The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the nucleus to the boundary of the surrounding cloud of electrons. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius. Depending on the definition, the term may apply only to isolated atoms, or also to atoms in condensed matter, covalently bound in molecules, or in ionized and excited states; and its value may be obtained through experimental measurements, or computed from theoretical models. Under some definitions, the value of the radius may depend on the atom's state and context.1

Atomic radii vary in a predictable and explicable manner across the periodic table. For instance, the radii generally decrease along each period (row) of the table, from the alkali metals to the noble gases; and increase down each group (column). The radius increases sharply between the noble gas at the end of each period and the alkali metal at the beginning of the next period. These trends of the atomic radii (and of various other chemical and physical properties of the elements) can be explained by the electron shell theory of the atom; they provided important evidence for the development and confirmation of quantum theory.

Atomic radii

Note: All measurements given are in picometers (pm). For more recent data on covalent radii see Covalent radius.

number symbol name empirical Calculated van der Waals Covalent (single bond) Covalent (triple bond) Metallic
1 H hydrogen 25 53 120 38 no data
2 He helium no data 31 140 32 no data
3 Li lithium 145 167 182 134 no data 152
4 Be beryllium 105 112 153 a 90 85 112
5 B boron 85 87 192 a 82 73
6 C carbon 70 67 170 77 60
7 N nitrogen 65 56 155 75 54
8 O oxygen 60 48 152 73 53
9 F fluorine 50 42 147 71 53
10 Ne neon no data 38 154 69 no data
11 Na sodium 180 190 227 154 no data 186
12 Mg magnesium 150 145 173 130 127 160
13 Al aluminium 125 118 184 a 118 111 143
14 Si silicon 110 111 210 111 102
15 P phosphorus 100 98 180 106 94
16 S sulfur 100 88 180 102 95
17 Cl chlorine 100 79 175 99 93
18 Ar argon 71 71 188 97 96
19 K potassium 220 243 275 196 no data 227
20 Ca calcium 180 194 231 a 174 133 197
21 Sc scandium 160 184 211 a 144 114 162 b
22 Ti titanium 140 176 no data 136 108 147
23 V vanadium 135 171 no data 125 106 134 b
24 Cr chromium 140 166 no data 127 103 128 b
25 Mn manganese 140 161 no data 139 103 127 b
26 Fe iron 140 156 no data 125 102 126 b
27 Co cobalt 135 152 no data 126 96 125 b
28 Ni nickel 135 149 163 121 101 124 b
29 Cu copper 135 145 140 138 120 128 b
30 Zn zinc 135 142 139 131 no data 134 b
31 Ga gallium 130 136 187 126 121 135 c
32 Ge germanium 125 125 211 a 122 114
33 As arsenic 115 114 185 119 106
34 Se selenium 115 103 190 116 107
35 Br bromine 115 94 185 114 110
36 Kr krypton no data 88 202 110 108
37 Rb rubidium 235 265 303 a 211 no data 248
38 Sr strontium 200 219 249 a 192 139 215
39 Y yttrium 180 212 no data 162 124 180 b
40 Zr zirconium 155 206 no data 148 121 160
41 Nb niobium 145 198 no data 137 116 146 b
42 Mo molybdenum 145 190 no data 145 113 139 b
43 Tc technetium 135 183 no data 156 110 136 b
44 Ru ruthenium 130 178 no data 126 103 134 b
45 Rh rhodium 135 173 no data 135 106 134 b
46 Pd palladium 140 169 163 131 112 137 b
47 Ag silver 160 165 172 153 137 144 b
48 Cd cadmium 155 161 158 148 no data 151 b
49 In indium 155 156 193 144 146 167
50 Sn tin 145 145 217 141 132
51 Sb antimony 145 133 206 a 138 127
52 Te tellurium 140 123 206 135 121
53 I iodine 140 115 198 133 125
54 Xe xenon no data 108 216 130 122
55 Cs caesium 260 298 343 a 225 no data 265
56 Ba barium 215 253 268 a 198 149 222
57 La lanthanum 195 no data no data 169 139 187 b
58 Ce cerium 185 no data no data no data 131 181.8 c
59 Pr praseodymium 185 247 no data no data 128 182.4 c
60 Nd neodymium 185 206 no data no data no data 181.4 c
61 Pm promethium 185 205 no data no data no data 183.4 c
62 Sm samarium 185 238 no data no data no data 180.4 c
63 Eu europium 185 231 no data no data no data 180.4 c
64 Gd gadolinium 180 233 no data no data 132 180.4 c
65 Tb terbium 175 225 no data no data no data 177.3 c
66 Dy dysprosium 175 228 no data no data no data 178.1 c
67 Ho holmium 175 no data no data no data no data 176.2 c
68 Er erbium 175 226 no data no data no data 176.1 c
69 Tm thulium 175 222 no data no data no data 175.9 c
70 Yb ytterbium 175 222 no data no data no data 176 c
71 Lu lutetium 175 217 no data 160 131 173.8 c
72 Hf hafnium 155 208 no data 150 122 159
73 Ta tantalum 145 200 no data 138 119 146 b
74 W tungsten 135 193 no data 146 115 139 b
75 Re rhenium 135 188 no data 159 110 137 b
76 Os osmium 130 185 no data 128 109 135 b
77 Ir iridium 135 180 no data 137 107 135.5 b
78 Pt platinum 135 177 175 128 110 138.5 b
79 Au gold 135 174 166 144 123 144 b
80 Hg mercury 150 171 155 149 no data 151 b
81 Tl thallium 190 156 196 148 150 170
82 Pb lead 180 154 202 147 137
83 Bi bismuth 160 143 207 a 146 135
84 Po polonium 190 135 197 a no data 129
85 At astatine no data no data 202 a no data 138
86 Rn radon no data 120 220 a 145 133
87 Fr francium no data no data 348 a no data no data no data
88 Ra radium 215 no data 283 a no data 159 no data
89 Ac actinium 195 no data no data no data 140
90 Th thorium 180 no data no data no data 136 179 b
91 Pa protactinium 180 no data no data no data 129 163 d
92 U uranium 175 no data 186 no data 118 156 e
93 Np neptunium 175 no data no data no data 116 155 e
94 Pu plutonium 175 no data no data no data no data 159 e
95 Am americium 175 no data no data no data no data 173 b
96 Cm curium no data no data no data no data no data 174 b
97 Bk berkelium no data no data no data no data no data 170 b
98 Cf californium no data no data no data no data no data 186+/- 2 b
99 Es einsteinium no data no data no data no data no data 186+/- 2 b
100 Fm fermium no data no data no data no data no data no data
101 Md mendelevium no data no data no data no data no data no data
102 No nobelium no data no data no data no data no data no data
103 Lr lawrencium no data no data no data no data no data no data
104 Rf rutherfordium no data no data no data no data 131 no data
105 Db dubnium no data no data no data no data 126 no data
106 Sg seaborgium no data no data no data no data 121 no data
107 Bh bohrium no data no data no data no data 119 no data
108 Hs hassium no data no data no data no data 118 no data
109 Mt meitnerium no data no data no data no data 113 no data
110 Ds darmstadtium no data no data no data no data 112 no data
111 Rg roentgenium no data no data no data no data 118 no data
112 Cn copernicium no data no data no data no data 130 no data
113 Uut ununtrium no data no data no data no data no data no data
114 Fl flerovium no data no data no data no data no data no data
115 Uup ununpentium no data no data no data no data no data no data
116 Lv livermorium no data no data no data no data no data no data
117 Uus ununseptium no data no data no data no data no data no data
118 Uuo ununoctium no data no data no data no data no data no data

Notes

  • The radius of an atom is not a uniquely defined property and depends on the definition. Data derived from other sources with different assumptions cannot be compared.
  • † to an accuracy of about 5 pm
  • (a) These radii are taken from M. Mantina, A.C. Chamberlin, R. Valero, C.J. Cramer, and D.G. Truhlar, J. Phys. Chem. 2009, 113, 5806.
  • (b) 12 coordinate
  • (c) gallium has an anomalous crystal structure
  • (d) 10 coordinate
  • (e) uranium, neptunium and plutonium have irregular structures

See also

References

  1. ^ Cotton, F. A.; Wilkinson, G. (1988). Advanced Inorganic Chemistry (5th ed.). Wiley. p. 1385. ISBN 978-0-471-84997-1. 

Data is as quoted at http://www.webelements.com/ from these sources:

Atomic radius (empirical)

Atomic radius (calculated)

Van der Waals radius

  • A. Bondi (1964). "van der Waals Volumes and Radii". J. Phys. Chem. 68: 441. doi:10.1021/j100785a001. 
  • M. Mantina, A.C. Chamberlin, R. Valero, C.J. Cramer, D.G. Truhlar (2009). "Consistent van der Waals Radii for the Whole Main Group". J. Phys. Chem. A 113 (19): 5806–12. doi:10.1021/jp8111556. PMID 19382751. 

Covalent radii (single bond)

More recent data can be found in Covalent radius. The above values are based on

  • R.T. Sanderson (1962). Chemical Periodicity. New York, USA: Reinhold. 
  • L.E. Sutton (ed.) (1965). "Supplement 1956–1959, Special publication No. 18". Table of interatomic distances and configuration in molecules and ions. London, UK: Chemical Society. 
  • J.E. Huheey, E.A. Keiter, and R.L. Keiter (1993). Inorganic Chemistry : Principles of Structure and Reactivity (4th ed.). New York, USA: HarperCollins. ISBN 0-06-042995-X. 
  • W.W. Porterfield (1984). Inorganic chemistry, a unified approach. Reading Massachusetts, USA: Addison Wesley Publishing Co. ISBN 0-201-05660-7. 
  • A.M. James and M.P. Lord (1992). Macmillan's Chemical and Physical Data. London, UK: Macmillan. ISBN 0-333-51167-0. 

Triple-bond covalent radii

Metallic radius

Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419. 








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