Data:Ionization energies of the elements (Z = 1–30)

Further information: Ionization energy

Z	Element	Ionization energy/eV
		I	II	III	IV	V	VI	VII	VIII	IX	X	XI	XII	XIII
1	Hydrogen	13.598
2	Helium	24.587	54.416
3	Lithium	5.392	75.638	122.451
4	Beryllium	9.322	18.211	155.893	217.713
5	Boron	8.298	25.154	37.930	259.368	340.217
6	Carbon	11.260	24.383	47.887	64.492	392.077	489.981
7	Nitrogen	14.534	29.601	47.448	77.472	97.888	352.057	667.029
8	Oxygen	13.618	35.116	54.934	77.412	113.896	138.116	739.315	871.387
9	Fluorine	17.422	34.970	62.707	87.138	114.240	157.161	185.182	953.886	1103.089
10	Neon	21.564	40.962	63.45	97.11	126.21	157.93	207.27	239.09	1195.797	1362.164
11	Sodium	5.139	47.286	71.64	98.91	138.39	172.15	208.47	264.18	299.87	1465.091	1648.659
12	Magnesium	7.646	15.035	80.143	109.24	141.26	186.50	224.94	265.90	327.95	367.53	1761.802	1962.613
13	Aluminium	5.986	18.828	28.447	119.99	153.71	190.47	241.43	284.59	330.21	398.57	442.07	2085.983	2304.080
14	Silicon	8.151	16.345	33.492	45.141	166.77	205.05	246.52	303.17	351.10	401.43	476.06	523.50	2437.676
15	Phosphorus	10.486	19.725	30.18	51.37	65.023	220.43	263.22	390.41	371.73	424.50	479.57	560.41	611.85
16	Sulfur	10.360	23.33	34.83	47.30	72.68	88.049	280.93	328.23	379.10	447.09	504.78	564.65	651.63
17	Chlorine	12.967	23.81	39.61	53.46	67.8	97.03	114.193	348.28	400.05	455.62	529.26	591.97	656.69
18	Argon	15.759	27.629	40.74	59.81	75.02	91.007	124.319	143.456	422.44	478.68	538.95	618.24	686.09
19	Potassium	4.341	31.625	45.72	60.91	82.66	100.0	117.56	154.86	175.814	503.44	564.13	629.09	714.02
20	Calcium	6.113	11.871	50.908	67.10	84.41	108.78	127.7	147.24	188.54	211.270	591.25	656.39	726.03
21	Scandium	6.54	12.80	24.76	73.47	91.66	111.1	138.0	158.7	180.02	225.32
22	Titanium	6.82	13.58	27.491	43.266	99.22	119.36	140.8	168.5	193.2	215.91
23	Vanadium	6.74	14.65	29.310	46.707	65.23	128.12	150.17	173.7	205.8	230.5
24	Chromium	6.766	16.50	30.96	49.1	69.3	90.56	161.1	184.7	209.3	244.4
25	Manganese	7.435	15.640	33.667	51.2	72.4	95	119.27	196.46	221.8	243.3
26	Iron	7.870	16.18	30.651	54.8	75.0	99	125	151.06	235.04	262.1
27	Cobalt	7.86	17.06	33.50	51.3	79.5	102	129	157	186.13	276
28	Nickel	7.635	18.168	35.17	54.9	75.5	108	133	162	193	224.5
29	Copper	7.726	20.292	36.83	55.2	79.9	103	139	166	199	232
30	Zinc	9.394	17.964	39.722	59.4	82.6	108	134	174	203	238

References

Moore, Charlotte E. Ionization potentials and ionization limits derived from the analyses of optical spectra. Natl. Stand. Ref. Data Ser., (U.S. Natl. Bur. Stand.) 1970, 34, 1–22, <http://www.nist.gov/data/nsrds/NSRDS-NBS34.pdf>.