Electron affinity (data page)

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Main article: Electron affinity

Elements[edit]

Note on negative electron affinities
Those elements listed with negative electron affinity are known to only have unstable negative ions. In some cases these negative ions can be prepared (and may have lifetimes on the order of microseconds to milliseconds) but they invariably autoionize after some time. The listed value in the table corresponds to a selected low-lying metastable state. This may or may not be the lowest energy resonance; for example in He there is a metastable state with 0.359 ms lifetime at 19.7 eV above the ground state of He, however there is also a lower energy resonance at 19.4 eV that only has a 10-13 s lifetime.[1]
Z Element Name Electron affinity (eV) References
1 H Hydrogen 0.754 195(19) [2]
2 He Helium -19.7 1s2s2p 4P5/2, 350 μs lifetime.[1]
3 Li Lithium 0.618 049(2) [3]
4 Be Beryllium -2.4 1s2s2p2 4P3/2, 43 μs lifetime.[1]
5 B Boron 0.279723(24) [4]
6 C Carbon 1.262118(20) [5]
7 N Nitrogen -1.4 2p4 1D, <1 μs lifetime.[1]
8 O Oxygen 1.4611134(9) [6]
9 F Fluorine 3.4011895(25) [7]
10 Ne Neon - no metastable states[1]
11 Na Sodium 0.547926(25) [8]
12 Mg Magnesium - no metastable states[1]
13 Al Aluminium 0.43283(5) [9]
14 Si Silicon 1.3895210(7) [6]
15 P Phosphorus 0.746 609(9) [10]
16 S Sulfur 2.0771040(6) [6]
17 Cl Chlorine 3.612724(27) [11]
18 Ar Argon -11.5 3p54s4p 4S3/2, 260 ns lifetime[1]
19 K Potassium 0.501459(12) [12]
20 Ca Calcium 0.02455(10) [13]
21 Sc Scandium 0.188(20) [14]
22 Ti Titanium 0.079(14) [15]
23 V Vanadium 0.526(12) [16]
24 Cr Chromium 0.67584(12) [17]
25 Mn Manganese -1 (theoretical) [1]
26 Fe Iron 0.151(3) [18]
27 Co Cobalt 0.6633(6) [19]
28 Ni Nickel 1.15716(12) [19]
29 Cu Copper 1.23578(4) [17]
30 Zn Zinc - No stable negative ion.[1]
31 Ga Gallium 0.43(3) [20]
32 Ge Germanium 1.232712(15) [5]
33 As Arsenic 0.8048(2) [21]
34 Se Selenium 2.020 604 6(11) [22]
35 Br Bromine 3.363590(3) [23]
36 Kr Krypton - no metastable states[1]
37 Rb Rubidium 0.485916(20) [24]
38 Sr Strontium 0.05206(6) [25]
39 Y Yttrium 0.307(12) [14]
40 Zr Zirconium 0.427(14) [16]
41 Nb Niobium 0.894(25) [16]
42 Mo Molybdenum 0.7473(3) [17]
43 Tc Technetium  ? May be unstable like Mn.[1]
44 Ru Ruthenium 1.076 (theoretical) [26]
45 Rh Rhodium 1.14289(20) [19]
46 Pd Palladium 0.56214(12) [19]
47 Ag Silver 1.30447(3) [17]
48 Cd Cadmium - No stable negative ion.[1]
49 In Indium 0.38392(6) [27]
50 Sn Tin 1.112070(2) [28]
51 Sb Antimony 1.047401(18) [29]
52 Te Tellurium 1.970876(7) [30]
53 I Iodine 3.0590463(38) [31]
54 Xe Xenon -0.056(10) (theoretical) [1]
55 Cs Caesium 0.47164(6) [4]
56 Ba Barium 0.14462(6) [32]
57 La Lanthanum 0.470(20) [1]
58 Ce Cerium 0.628(10) [33]
59 Pr Praseodymium 0.962(24) [1]
60 Nd Neodymium 0.162 (theoretical) [34]
61 Pm Promethium 0.129 (theoretical) [34]
62 Sm Samarium 0.162 (theoretical) [34]
63 Eu Europium 0.116 (theoretical) [34]
64 Gd Gadolinium 0.137 (theoretical) [34]
65 Tb Terbium 0.436 (theoretical) [34]
66 Dy Dysprosium 0.352 (theoretical) [34]
67 Ho Holmium 0.338 (theoretical) [34]
68 Er Erbium 0.312 (theoretical) [34]
69 Tm Thulium 0.016 (theoretical) [34]
70 Yb Ytterbium 0.00(3) [1]
71 Lu Lutetium 0.34(1) [1]
72 Hf Hafnium  ? [1]
73 Ta Tantalum 0.323(12) [16]
74 W Tungsten 0.81626(8) [35]
75 Re Rhenium  ? May be unstable like Mn.[1]
76 Os Osmium 1.07780(12) [36]
77 Ir Iridium 1.56436(15) [37]
78 Pt Platinum 2.12510(5) [37]
79 Au Gold 2.308610(25) [38]
80 Hg Mercury - No stable negative ion.[1]
81 Tl Thallium 0.377(13) [39]
82 Pb Lead 0.364(8) [16]
83 Bi Bismuth 0.942362(13) [40]
84 Po Polonium 1.9(3) (theoretical) [41]
85 At Astatine 2.8(2) (theoretical) [41]

Electron affinity can be defined in two equivalent ways. First, as the energy [that is] released by adding an electron to a gaseous atom. (The energy -or electron affinity- is a scalar quantity and the direction of that energy -released- defines a reaction for which the change in energy ΔE is a negative quantity). The electron affinity is also defined in the case of electron capture as E(initial) – E(final) in order to maintain the positive value.[42] The reverse definition is that the electron affinity is the energy required to remove an electron from a gaseous anion (still a positive quantity, but in which the change in energy ΔE is also a positive quantity). Either convention can be used in practice, but must be consistent in according a scalar, i.e. positive number to the electron affinity. A negative sign appearing with a value for electron affinity indicates a change in direction, either that electron capture requires energy or removal releases energy.

Z Element Electron affinity
(kJ/mol)
References
1 Hydrogen 72.77 [2][43]
3 Lithium 59.62 [3][8][44]
5 Boron 26.99 [4]
6 Carbon 121.78 [5]
8 Oxygen 141.004 [8][45][46]
9 Fluorine 328.165 [7][23]
11 Sodium 52.87 [8]
13 Aluminium 41.86 [9]
14 Silicon 134.07 [5][7]
15 Phosphorus 72.03 [8]
16 Sulfur 200.410 [45]
17 Chlorine 349 [47]
19 Potassium 48.38 [12][48]
20 Calcium 2.37 [13]
21 Scandium 18(2) [14]
22 Titanium 8.4(7) [49]
23 Vanadium 51. [8]
24 Chromium 65.2 [17]
26 Iron 14.6(3) [18]
27 Cobalt 64.0 [19]
28 Nickel 111.6 [19]
29 Copper 119.24 [17]
31 Gallium 41(3) [20]
32 Germanium 118.94 [5]
33 Arsenic 78.5(7) [50]
34 Selenium 194.97 [22]
35 Bromine 342.54 [23]
37 Rubidium 46.89 [24]
38 Strontium 5.02 [25]
39 Yttrium 30. [14]
40 Zirconium 41. [8]
41 Niobium 86(2) [8]
42 Molybdenum 72.3 [17]
44 Ruthenium 101.0 [26]
45 Rhodium 110.3 [19]
46 Palladium 54.24 [19]
47 Silver 125.86 [17]
49 Indium 39 [51]
50 Tin 107.30 [5]
51 Antimony 101.06 [29]
52 Tellurium 190.16 [8][30]
53 Iodine 295 [47]
55 Caesium 45.51 [48][52]
56 Barium 13.95 [32]
57 Lanthanum 45(2) [53]
58 Cerium 92(2) [54]
69 Thulium 99(2) [55]
71 Lutetium 33 [56]
73 Tantalum 31 [8]
74 Tungsten 79 [8][57]
76 Osmium 104.0 [36]
77 Iridium 150.9 [37]
78 Platinum 205.04 [37]
79 Gold 222.75 [8]
81 Thallium 36 [39]
82 Lead 35 [8]
83 Bismuth 90.92 [40]

Molecules[edit]

Molecule Electron affinity
(kJ/mol)
References
Diatomics  
Dibromine 244 Janousek & Brauman (1979)
Dichlorine 227 Janousek & Brauman (1979)
Difluorine 297 Janousek & Brauman (1979)
Diiodine 246 Janousek & Brauman (1979)
Dioxygen 43 CRC Handbook
Iodine bromide 251 Janousek & Brauman (1979)
Lithium chloride 59 Janousek & Brauman (1979)
Nitric oxide 2 Janousek & Brauman (1979)
Triatomics  
Nitrogen dioxide 222 Janousek & Brauman (1979)
Sulfur dioxide 105 Janousek & Brauman (1979)
Larger polyatomics  
Benzene −110 Janousek & Brauman (1979)
p-Benzoquinone 129 CRC Handbook
Boron trifluoride 255 CRC Handbook
Nitric acid 59 Janousek & Brauman (1979)
Nitromethane 38 Janousek & Brauman (1979)
Phosphoryl chloride 134 Janousek & Brauman (1979)
Sulfur hexafluoride 138 CRC Handbook
Tetracyanoethylene 278 CRC Handbook
Tungsten hexafluoride 264 CRC Handbook
Uranium hexafluoride 280 CRC Handbook

Bibliography[edit]

  • CRC Handbook of Chemistry and Physics (62nd Edn. (1981); Weast, Robert C. (ed)). Boca Raton, FL: CRC Press. "Section E, General Physical Constants; Electron Affinities".
  • Janousek, B. K.; Brauman, J. I. (1979). in Gas Phase Ion Chemistry (Bowers, M. T. (Ed.)), Vol. 2. New York: Academic Press. p. 53.

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See also[edit]