Ground levels and ionization energies for the neutral atoms

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Z				Element		Ground-state configuration						Ground    level	Ionization energy (eV)			Reference for ionization energy
1	H	Hydrogen	1s					2S1/2	13.5984		(1983), (1985)
2	He	Helium	1s2					1S0	24.5874		(1997), (1998)
3	Li	Lithium	1s2	2s				2S1/2	5.3917	Lorenzen & Niemax (1982)
4	Be	Beryllium	1s2	2s2				1S0	9.3227	Beigang et al. (1983)
5	B	Boron	1s2	2s2	2p			2Po1/2	8.2980	(1970), (1974)
6	C	Carbon	1s2	2s2	2p2			3P0	11.2603	Johansson (1966)
7	N	Nitrogen	1s2	2s2	2p3			4So3/2	14.5341	Eriksson & Pettersson (1971)
8	O	Oxygen	1s2	2s2	2p4			3P2	13.6181	Eriksson & Isberg (1968)
9	F	Fluorine	1s2	2s2	2p5			2Po3/2	17.4228	(1949), (1969)
10	Ne	Neon	1s2	2s2	2p6			1S0	21.5645	Kaufman & Minnhagen (1972)
11	Na	Sodium	[Ne]	3s				2S1/2	5.1391	(1992), (1998)
12	Mg	Magnesium	[Ne]	3s2				1S0	7.6462	(1987), (1991)
13	Al	Aluminum	[Ne]	3s2	3p			2Po1/2	5.9858	(1990), (1991)
14	Si	Silicon	[Ne]	3s2	3p2			3P0	8.1517	Martin & Zalubas (1983)
15	P	Phosphorus	[Ne]	3s2	3p3			4So3/2	10.4867	Svendenius (1980)
16	S	Sulfur	[Ne]	3s2	3p4			3P2	10.3600	Martin et al. (1990)
17	Cl	Chlorine	[Ne]	3s2	3p5			2Po3/2	12.9676	Radziemski & Kaufman (1969)
18	Ar	Argon	[Ne]	3s2	3p6			1S0	15.7596	Velchev et al. (1999)
19	K	Potassium	[Ar]		4s			2S1/2	4.3407	(1983), (1985)
20	Ca	Calcium	[Ar]		4s2			1S0	6.1132	Sugar & Corliss (1985)
21	Sc	Scandium	[Ar]	3d	4s2			2D3/2	6.5615	Sugar & Corliss (1985)
22	Ti	Titanium	[Ar]	3d 2	4s2			3F2	6.8281	Sohl et al. (1990)
23	V	Vanadium	[Ar]	3d 3	4s2			4F3/2	6.7462	James et al. (1994)
24	Cr	Chromium	[Ar]	3d 5	4s			7S3	6.7665	Sugar & Corliss (1985)
25	Mn	Manganese	[Ar]	3d 5	4s2			6S5/2	7.4340	Sugar & Corliss (1985)
26	Fe	Iron	[Ar]	3d 6	4s2			5D4	7.9024	Sugar & Corliss (1985)
27	Co	Cobalt	[Ar]	3d 7	4s2			4F9/2	7.8810	Page & Gudeman (1990)
28	Ni	Nickel	[Ar]	3d 8	4s2			3F4	7.6398	Page & Gudeman (1990)
29	Cu	Copper	[Ar]	3d10	4s			2S1/2	7.7264	(1948), (1980), (1999)
30	Zn	Zinc	[Ar]	3d10	4s2			1S0	9.3942	Brown et al. (1975)
31	Ga	Gallium	[Ar]	3d10	4s2	4p		2Po1/2	5.9993	Tursunov & Eshkobilov (1985)
32	Ge	Germanium	[Ar]	3d10	4s2	4p2		3P0	7.8994	Sugar & Musgrove (1993)
33	As	Arsenic	[Ar]	3d10	4s2	4p3		4So3/2	9.7886	Bhatia & Jones (1971)
34	Se	Selenium	[Ar]	3d10	4s2	4p4		3P2	9.7524	(1974), (1983)
35	Br	Bromine	[Ar]	3d10	4s2	4p5		2Po3/2	11.8138	(1961), (1967)
36	Kr	Krypton	[Ar]	3d10	4s2	4p6		1S0	13.9996	Sugar & Musgrove (1991)
37	Rb	Rubidium	[Kr]		5s			2S1/2	4.1771	(1961), (1983)
38	Sr	Strontium	[Kr]		5s2			1S0	5.6949	Rubbmark & Borgstrom (1978)
39	Y	Yttrium	[Kr]	4d	5s2			2D3/2	6.2173	(1973), (2000)
40	Zr	Zirconium	[Kr]	4d 2	5s2			3F2	6.6339	Hackett et al. (1986)
41	Nb	Niobium	[Kr]	4d 4	5s			6D1/2	6.7589	Rayner et al. (1987)
42	Mo	Molybdenum	[Kr]	4d 5	5s			7S3	7.0924	Rayner et al. (1987)
43	Tc	Technetium	[Kr]	4d 5	5s2			6S5/2	7.28	Finkelnburg & Humbach (1955)
44	Ru	Ruthenium	[Kr]	4d 7	5s			5F5	7.3605	(1979), (1988)
45	Rh	Rhodium	[Kr]	4d 8	5s			4F9/2	7.4589	Callender et al. (1988)
46	Pd	Palladium	[Kr]	4d10				1S0	8.3369	Callender et al. (1988)
47	Ag	Silver	[Kr]	4d10	5s			2S1/2	7.5762	(1940), (1999)
48	Cd	Cadmium	[Kr]	4d10	5s2			1S0	8.9938	Brown et al. (1975)
49	In	Indium	[Kr]	4d10	5s2	5p		2Po1/2	5.7864	Dönszelmann & Neijzen (1983)
50	Sn	Tin	[Kr]	4d10	5s2	5p2		3P0	7.3439	Brown et al. (1977)
51	Sb	Antimony	[Kr]	4d10	5s2	5p3		4So3/2	8.6084	Beigang & Wynne (1986)
52	Te	Tellurium	[Kr]	4d10	5s2	5p4		3P2	9.0096	Cantú et al. (1986)
53	I	Iodine	[Kr]	4d10	5s2	5p5		2Po3/2	10.4513	Minnhagen (1962)
54	Xe	Xenon	[Kr]	4d10	5s2	5p6		1S0	12.1298	(1985), (2001)
55	Cs	Cesium	[Xe]			6s		2S1/2	3.8939	Weber & Sansonetti (1984)
56	Ba	Barium	[Xe]			6s2		1S0	5.2117	Post et al. (1985)
57	La	Lanthanum	[Xe]		5d	6s2		2D3/2	5.5769	Garton & Wilson (1966)
58	Ce	Cerium	[Xe]	4f	5d	6s2		1Go4	5.5387	Worden et al. (1978)
59	Pr	Praseodymium	[Xe]	4f 3		6s2		4Io9/2	5.473	Worden et al. (1978)
60	Nd	Neodymium	[Xe]	4f 4		6s2		5I4	5.5250	Worden et al. (1978)
61	Pm	Promethium	[Xe]	4f 5		6s2		6Ho5/2	5.582	Worden et al. (1978)
62	Sm	Samarium	[Xe]	4f 6		6s2		7F0	5.6437	T. Jaysekharan et al. (2000)
63	Eu	Europium	[Xe]	4f 7		6s2		8So7/2	5.6704	Nakhate et al. (2000)
64	Gd	Gadolinium	[Xe]	4f 7	5d	6s2		9Do2	6.1498	Miyabe et al. (1998)
65	Tb	Terbium	[Xe]	4f 9		6s2		6Ho15/2	5.8638	Worden et al. (1978)
66	Dy	Dysprosium	[Xe]	4f 10		6s2		5I8	5.9389	Worden et al. (1978)
67	Ho	Holmium	[Xe]	4f 11		6s2		4Io15/2	6.0215	Worden et al. (1978)
68	Er	Erbium	[Xe]	4f 12		6s2		3H6	6.1077	Worden et al. (1978)
69	Tm	Thulium	[Xe]	4f 13		6s2		2Fo7/2	6.1843	Camus (1971)
70	Yb	Ytterbium	[Xe]	4f 14		6s2		1S0	6.2542	Aymar et al. (1980)
71	Lu	Lutetium	[Xe]	4f 14	5d	6s2		2D3/2	5.4259	(1972), (1989)
72	Hf	Hafnium	[Xe]	4f 14	5d 2	6s2		3F2	6.8251	Callender et al. (1988)
73	Ta	Tantalum	[Xe]	4f 14	5d 3	6s2		4F3/2	7.5496	Simard et al. (1994)
74	W	Tungsten	[Xe]	4f 14	5d 4	6s2		5D0	7.8640	Campbell-Miller & Simard (1996)
75	Re	Rhenium	[Xe]	4f 14	5d 5	6s2		6S5/2	7.8335	Campbell-Miller & Simard (1996)
76	Os	Osmium	[Xe]	4f 14	5d 6	6s2		5D4	8.4382	Colarusso et al. (1997)
77	Ir	Iridium	[Xe]	4f 14	5d 7	6s2		4F9/2	8.9670	Colarusso et al. (1997)
78	Pt	Platinum	[Xe]	4f 14	5d 9	6s		3D3	8.9588	(1995), (2000)
79	Au	Gold	[Xe]	4f 14	5d10	6s		2S1/2	9.2255	(1978), (1999)
80	Hg	Mercury	[Xe]	4f 14	5d10	6s2		1S0	10.4375	Baig (1983)
81	Tl	Thallium	[Xe]	4f 14	5d10	6s2	6p	2Po1/2	6.1082	Baig & Connerade (1985)
82	Pb	Lead	[Xe]	4f 14	5d10	6s2	6p2	3P0	7.4167	Brown et al. (1977)
83	Bi	Bismuth	[Xe]	4f 14	5d10	6s2	6p3	4So3/2	7.2855	Matthews et al. (1989)
84	Po	Polonium	[Xe]	4f 14	5d10	6s2	6p4	3P2	8.414	Charles (1966)
85	At	Astatine	[Xe]	4f 14	5d10	6s2	6p5	2Po3/2
86	Rn	Radon	[Xe]	4f 14	5d10	6s2	6p6	1S0	10.7485	(1933), (1970)
87	Fr	Francium	[Rn]			7s		2S1/2	4.0727	Arnold et al. (1990)
88	Ra	Radium	[Rn]			7s2		1S0	5.2784	Amstrong et al. (1980)
89	Ac	Actinium	[Rn]		6d	7s2		2D3/2	5.17	(1955), (1974)
90	Th	Thorium	[Rn]		6d 2	7s2		3F2	6.3067	Köhler et al. (1997)
91	Pa	Protactinium	[Rn]	5f 2(3H4) 6d 7s2				(4,3/2)11/2	5.89	Sugar (1974)
92	U	Uranium	[Rn]	5f 3(4Io9/2) 6d 7s2				(9/2,3/2)o6	6.1941	Coste et al. (1982)
93	Np	Neptunium	[Rn]	5f 4(5I4) 6d 7s2				(4,3/2)11/2	6.2657	(1979), (1994), (1997)
94	Pu	Plutonium	[Rn]	5f 6		7s2		7F0	6.0260	(1993), (1997)
95	Am	Americium	[Rn]	5f 7		7s2		8So7/2	5.9738	Köhler et al. (1997)
96	Cm	Curium	[Rn]	5f 7	6d	7s2		9Do2	5.9914	Köhler et al. (1997)
97	Bk	Berkelium	[Rn]	5f 9		7s2		6Ho15/2	6.1979	Köhler et al. (1997)
98	Cf	Californium	[Rn]	5f 10		7s2		5I8	6.2817	Köhler et al. (1997)
99	Es	Einsteinium	[Rn]	5f 11		7s2		4Io15/2	6.42	Sugar (1974)
100	Fm	Fermium	[Rn]	5f 12		7s2		3H6	6.50	Sugar (1974)
101	Md	Mendelevium	[Rn]	5f 13		7s2		2Fo7/2	6.58	Sugar (1974)
102	No	Nobelium	[Rn]	5f 14		7s2		1S0	6.65	Sugar (1974)
103	Lr	Lawrencium	[Rn]	5f 14		7s2	7p ?	2Po1/2 ?	4.9 ?	Eliav et al. (1995)
104	Rf	Rutherfordium	[Rn]	5f 14	6d 2	7s2 ?		3F2 ?	6.0 ?	Eliav et al. (1995)