电子亲合能

在一般化学与原子物理学中，电子亲合能（或电子亲和势、电子亲和力，electron affinity，E_ea）的定义是，将单个电子结合到电中性的气态原子或分子上所释放的能量^[1]：

X(g) + e⁻ → X⁻(g) + E_ea

注意在此定义下，大多数元素原子的电子亲和能为正数，即结合电子的过程是放热的。这里定义的电子亲和能的正负号选取和一般热力学的定义相反。

在固体物理学之中，对于一表面的电子亲合能定义不同。

元素的电子亲合能

并非所有的元素的电子亲合能均为正，电子亲合能为正表示其 -1 价的离子需吸收能量才能变为电中性的原子（早期的教科书写有些元素，例如稀有气体，其电子亲合能为负，此说法并未被现代的化学家接受）。若其阴离子较不稳定，容易变成原子，则其电子亲合能较低。元素中氯的电子亲合能最高，汞和稀有气体等元素的电子亲合能都接近零。一般来说，非金属的电子亲合能都比金属高。

总的来说，同一周期从左至右，价壳层电子递增，使得原子稳定性上升，原子半径递减，对电子的吸引能力渐强，因而电子亲合能递增；同族元素从上到下，因原子半径的增大，而且总电子数增加，原子稳定性下降，元素电负性值递减。 实际上，随核电荷数递增或同族元素从上到下，电子亲和能的变化并不单调。

带有电子亲合能数据的元素周期表

下列数据以kJ/mol为单位。带星号的元素在量子力学基态被认为有接近零的电子亲合能。

周期

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

电子层

Ｏ族电子数

族

I A

0

1

73 H 氢

* He 氦

K

2

II A

III A

IV A

V A

VI A

VII A

2

60 Li 锂

* Be 铍

27 B 硼

122 C 碳

−7 N 氮

141 O 氧

328 F 氟

* Ne 氖

L K

8 2

3

53 Na 钠

* Mg 镁

42 Al 铝

134 Si 硅

72 P 磷

200 S 硫

349 Cl 氯

* Ar 氩

M L K

8 8 2

III B

IV B

V B

VI B

VII B

VIII

I B

II B

4

48 K 钾

2 Ca 钙

18 Sc 钪

8 Ti 钛

51 V 钒

65 Cr 铬

0 Mn 锰

15 Fe 铁

64 Co 钴

112 Ni 镍

119 Cu 铜

* Zn 锌

41 Ga 镓

119 Ge 锗

79 As 砷

195 Se 硒

325 Br 溴

* Kr 氪

N M L K

8 18 8 2

5

47 Rb 铷

5 Sr 锶

30 Y 钇

41 Zr 锆

86 Nb 铌

72 Mo 钼

53 Tc 锝

101 Ru 钌

110 Rh 铑

54 Pd 钯

126 Ag 银

* Cd 镉

39 In 铟

107 Sn 锡

101 Sb 锑

190 Te 碲

295 I 碘

* Xe 氙

O N M L K

8 18 18 8 2

6

46 Cs 铯

14 Ba 钡

镧系

* Hf 铪

31 Ta 钽

79 W 钨

15 Re 铼

104 Os 锇

150 Ir 铱

205 Pt 铂

223 Au 金

* Hg 汞

36 Tl 铊

35 Pb 铅

91 Bi 铋

190 Po 钋

270 At 砹

* Rn 氡

P O N M L K

8 18 32 18 8 2

7

Fr 钫

Ra 镭

锕系

Rf 𬬻

Db 𬭊

Sg 𬭳

Bh 𬭛

Hs 𬭶

Mt 鿏

Ds 𫟼

Rg 𬬭

Cn 鿔

Nh 鿭

Fl 𫓧

Mc 镆

Lv 𫟷

Ts 鿬

Og 鿫

镧系元素

45 La 镧

92 Ce 铈

Pr 镨

Nd 钕

Pm 钷

Sm 钐

Eu 铕

Gd 钆

Tb 铽

Dy 镝

Ho 钬

Er 铒

99 Tm 铥

Yb 镱

33 Lu 镥

锕系元素

Ac 锕

Th 钍

Pa 镤

U 铀

Np 镎

Pu 钚

Am 镅

Cm 锔

Bk 锫

Cf 锎

Es 锿

Fm 镄

Md 钔

No 锘

Lr 铹

碱金属	碱土金属	镧系元素	锕系元素	过渡金属
主族金属	类金属	非金属	卤素	稀有氣體

列表及参考资料

元素	电子亲合能 (kJ/mol)	参考资料
氢	72.77	Pekeris (1962). Lykke, Murray & Lineberger (1991).
氦	-48±20（估计）	[2]
锂	59.62	Hotop & Lineberger (1985). Dellwo et al. (1992). Haeffler et al. (1996a).
铍	-48±20（估计）	[2]
硼	26.99	Scheer, Bilodeau & Haugen (1998).
碳	121.78	Scheer et al. (1998a).
氮	-6.8	[2]
氧	141.004	Hotop & Lineberger (1985). Blondel (1995). Valli, Blondel & Delsart (1999).
氟	328.165	Blondel et al. (1989). Blondel, Delsart & Goldfarb (2001).
氖	-116±19（估计）	[2]
钠	52.87	Hotop & Lineberger (1985)
铝	41.86	Scheer et al. (1998b)
硅	134.07	Scheer et al. (1998a). Blondel, Delsart & Goldfarb (2001).
磷	72.03	Hotop & Lineberger (1985).
硫	200.410	Blondel (1995).
氯	349	Moore (1970).
钾	48.38	Slater et al. (1978). Andersson et al. (2000).
钙	2.37	Petrunin et al. (1996).
钪	18(2)	Feigerle, Herman & Lineberger (1981).
钛	8.4(7)	Ilin, Sakharov & Serenkov (1987).
钒	51	Hotop & Lineberger (1985).
铬	65.2	Bilodeau, Scheer & Haugen (1998).
铁	14.6(3)	Leopold & Lineberger (1986).
钴	64.0	Scheer et al. (1998c).
镍	111.6	Scheer et al. (1998c).
铜	119.24	Bilodeau, Scheer & Haugen (1998).
镓	41(3)	Williams et al. (1998a).
锗	118.94	Scheer et al. (1998a).
砷	78.5(7)	Lippa et al. (1998).
硒	194.97	Hotop & Lineberger (1985). Mansour et al. (1988).
溴	342.54	Blondel et al. (1989).
铷	46.89	Frey, Breyer & Hotop (1978).
锶	5.02	Andersen et al. (1997).
钇	30	Feigerle, Herman & Lineberger (1981).
锆	41	Hotop & Lineberger (1985).
铌	86(2)	Hotop & Lineberger (1985).
钼	72.3	Bilodeau, Scheer & Haugen (1998).
钌	101.0	Norquist et al. (1999).
铑	110.3	Scheer et al. (1998c).
钯	54.24	Scheer et al. (1998c).
银	125.86	Biladeau, Scheer & Haugen (1998).
铟	39	Williams et al. (1998b).
锡	107.30	Scheer et al. (1998a).
锑	101.06	Scheer, Haugen & Beck (1997).
碲	190.16	Hotop & Lineberger (1985). Haeffler et al. (1996b).
碘	295	Moore (1970).
铯	45.51	Slater et al. (1978). Scheer et al. (1998d).
钡	13.95	Petrunin et al. (1995).
镧	45(2)	Covington et al. (1998).
铈	92(2)	Davis & Thompson (2002a).
铥	99(2)	Davis & Thompson (2002b).
镏	33	Davis & Thompson (2001).
铪	0.00	Periodic Table of the Elements(2017)
钽	31	Hotop & Lineberger (1985).
钨	79	Hotop & Lineberger (1985). Bengali et al. (1992).
锇	104.0	Biladeau & Haugen (2000).
铱	150.9	Biladeau et al. (1999).
铂	205.04	Biladeau et al. (1999).
金	222.75	Hotop & Lineberger (1985).
铊	36	Carpenter, Covington & Thompson (2000).
铅	35	Hotop & Lineberger (1985).
铋	90.92	Biladeau & Haugen (2001).
钋	183.3	[3]
砹	270.1	[3]

分子的电子亲合能

电子亲合能 E_ea 的定义也可以延伸到分子。如苯和萘的电子亲合能为负值，而蒽 、菲、芘的电子亲合能为正值。电脑模拟实验证实六氰基苯 C₆(CN)₆ 的电子亲合能较富勒烯要高。^[4]

列表及参考资料

分子	电子亲合能 (kJ/mol)	参考资料
双原子分子
溴分子	244	Janousek & Brauman (1979)
氯气	227	Janousek & Brauman (1979)
氟气	297	Janousek & Brauman (1979)
碘分子	246	Janousek & Brauman (1979)
氧气	43	CRC Handbook
溴化碘	251	Janousek & Brauman (1979)
氯化锂	59	Janousek & Brauman (1979)
一氧化氮	2	Janousek & Brauman (1979)
三原子分子
二氧化氮	222	Janousek & Brauman (1979)
二氧化硫	105	Janousek & Brauman (1979)
多原子分子
苯	−110	Janousek & Brauman (1979)
1,4-苯二酮	129	CRC Handbook
三氟化硼	255	CRC Handbook
硝酸	59	Janousek & Brauman (1979)
硝基甲烷	38	Janousek & Brauman (1979)
三氯化磷	134	Janousek & Brauman (1979)
六氟化硫	138	CRC Handbook
四氰乙烯	278	CRC Handbook
六氟化钨	264	CRC Handbook
六氟化铀	280	CRC Handbook

参见

• Koopmans' theorem
• One-electron reduction
• 游离能
• 电负性
• 价电子

注释

1. 国际纯化学和应用化学联合会，化学术语概略，第二版。（金皮书）(1997)。在线校正版: (2006–) "Electron affinity"。doi:10.1351/goldbook.E01977
2. Bratsch, S.G.; Lagowski, J.J. Predicted stabilities of monatomic anions in water and liquid ammonia at 298.15 K.. Polyhedron. 1986, 5 (11): 1763–1770. doi:10.1016/S0277-5387(00)84854-8.
3. 存档副本. [2019-12-28]. （原始内容存档于2020-02-03）.
4. Remarkable electron accepting properties of the simplest benzenoid cyanocarbons: hexacyanobenzene, octacyanonaphthalene and decacyanoanthracene Xiuhui Zhang, Qianshu Li, Justin B. Ingels, Andrew C. Simmonett, Steven E. Wheeler, Yaoming Xie, R. Bruce King, Henry F. Schaefer III and F. Albert Cotton Chemical Communications, 2006, 758 - 760 Abstract

参考资料

以下许多参考资料的文章名称会连结至参考资料的本文，不过需要订阅或付费才能阅读。(摘要)会连结到参考资料的摘要，不需付费即可阅读。

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外部链接

• Electron affinity （页面存档备份，存于互联网档案馆）, IUPAC 金色书的定义
• Article about Electron Affinity