Electron affinity (data page)
Z Element Name Electron affinity ( eV ) Electron affinity ( kJ/mol )
1 H Hydrogen 0.754 195 ( 19 ) 72.769 ( 2 )
1 H Deuterium 0.754 59 ( 8 ) 72.807 ( 8 )
2 He Helium -0.5 ( 2 ) -48 ( 20 )
3 Li Lithium 0.618 049 ( 22 ) 59.632 6 ( 21 )
4 Be Beryllium -0.5 ( 2 ) -48 ( 20 )
5 B Boron 0.279 723 ( 25 ) 26.989 ( 3 )
6 C Carbon 1.262 122 6 ( 11 ) 121.776 3 ( 1 )
6 C Carbon 1.262 113 6 ( 12 ) 121.775 5 ( 2 )
7 N Nitrogen -0.07 -6.8
8 O Oxygen 1.461 113 6 ( 9 ) 140.976 0 ( 2 )
8 O Oxygen 1.461 108 ( 4 ) 140.975 5 ( 3 )
8 O Oxygen 1.461 105 ( 3 ) 140.975 2 ( 3 )
9 F Fluorine 3.401 189 8 ( 24 ) 328.164 9 ( 3 )
10 Ne Neon -1.2 ( 2 ) -116 ( 19 )
11 Na Sodium 0.547 926 ( 25 ) 52.867 ( 3 )
12 Mg Magnesium -0.4 ( 2 ) -40 ( 19 )
13 Al Aluminium 0.432 83 ( 5 ) 41.762 ( 5 )
14 Si Silicon 1.389 521 2 ( 8 ) 134.068 4 ( 1 )
15 P Phosphorus 0.746 607 ( 10 ) 72.037 ( 1 )
16 S Sulfur 2.077 104 2 ( 6 ) 200.410 1 ( 1 )
Elements
Electron affinity can be defined in two equivalent ways . First , as the energy that is released by adding an electron to an isolated gaseous atom . The second ( reverse ) definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion . Either convention can be used . [ 1 ] Whereas ionization energies are always concerned with the formation of positive ions , electron affinities are the negative ion equivalent . Negative electron affinities can be used in those cases where electron capture requires energy , i.e . when capture can occur only if the impinging electron has a kinetic energy large enough to excite a resonance of the atom-plus-electron system . Conversely electron removal from the anion formed in this way releases energy , which is carried out by the freed electron as kinetic energy . Negative ions formed in these cases are always unstable . They may have lifetimes of the order of microseconds to milliseconds , and invariably autodetach after some time .
This page deals with the electron affinity as a property of isolated atoms or molecules (i.e. in the gas phase). Solid state electron affinities are not listed here.