National Institute of Standards and Technology (NIST)
NIST Atomic Spectra Database -- Ionization Energies Data
http://www.nist.gov/pml/data/ion_energy.cfm


1   Hydrogen    1s   2S1/2
2   Helium  1s2      1S0
3   Lithium     1s22s    2S1/2
4   Beryllium   1s22s2   1S0
5   Boron   1s22s22p     2P°1/2
6   Carbon  1s22s22p2    3P0
7   Nitrogen    1s22s22p3    4S°3/2
8   Oxygen  1s22s22p4    3P2
9   Fluorine    1s22s22p5    2P°3/2
10  Neon    1s22s22p6    1S0
11  Sodium  [Ne]3s   2S1/2
12  Magnesium   [Ne]3s2      1S0
13  Aluminum    [Ne]3s23p    2P°1/2
14  Silicon     [Ne]3s23p2   3P0
15  Phosphorus  [Ne]3s23p3   4S°3/2
16  Sulfur  [Ne]3s23p4   3P2
17  Chlorine    [Ne]3s23p5   2P°3/2
18  Argon   [Ne]3s23p6   1S0
19  Potassium   [Ar]4s   2S1/2
20  Calcium     [Ar]4s2      1S0
21  Scandium    [Ar]3d4s2    2D3/2
22  Titanium    [Ar]3d24s2   3F2
23  Vanadium    [Ar]3d34s2   4F3/2
24  Chromium    [Ar]3d54s    7S3
25  Manganese   [Ar]3d54s2   6S5/2
26  Iron    [Ar]3d64s2   5D4
27  Cobalt  [Ar]3d74s2   4F9/2
28  Nickel  [Ar]3d84s2   3F4
29  Copper  [Ar]3d104s   2S1/2
30  Zinc    [Ar]3d104s2      1S0
31  Gallium     [Ar]3d104s24p    2P°1/2
32  Germanium   [Ar]3d104s24p2   3P0
33  Arsenic     [Ar]3d104s24p3   4S°3/2
34  Selenium    [Ar]3d104s24p4   3P2
35  Bromine     [Ar]3d104s24p5   2P°3/2
36  Krypton     [Ar]3d104s24p6   1S0
37  Rubidium    [Kr]5s   2S1/2
38  Strontium   [Kr]5s2      1S0
39  Yttrium     [Kr]4d5s2    2D3/2
40  Zirconium   [Kr]4d25s2   3F2
41  Niobium     [Kr]4d45s    6D1/2
42  Molybdenum  [Kr]4d55s    7S3
43  Technetium  [Kr]4d55s2   6S5/2
44  Ruthenium   [Kr]4d75s    5F5
45  Rhodium     [Kr]4d85s    4F9/2
46  Palladium   [Kr]4d10     1S0
47  Silver  [Kr]4d105s   2S1/2
48  Cadmium     [Kr]4d105s2      1S0
49  Indium  [Cd]5p   2P°1/2
50  Tin     [Cd]5p2      3P0
51  Antimony    [Cd]5p3      4S°3/2
52  Tellurium   [Cd]5p4      3P2
53  Iodine  [Cd]5p5      2P°3/2
54  Xenon   [Cd]5p6      1S0
55  Cesium  [Xe]6s   2S1/2
56  Barium  [Xe]6s2      1S0
57  Lanthanum   [Xe]5d6s2    2D3/2
58  Cerium  [Xe]4f5d6s2      1G°4
59  Praseodymium    [Xe]4f36s2   4I°9/2
60  Neodymium   [Xe]4f46s2   5I4
61  Promethium  [Xe]4f56s2   6H°5/2
62  Samarium    [Xe]4f66s2   7F0
63  Europium    [Xe]4f76s2   8S°7/2
64  Gadolinium  [Xe]4f75d6s2     9D°2
65  Terbium     [Xe]4f96s2   6H°15/2
66  Dysprosium  [Xe]4f106s2      5I8
67  Holmium     [Xe]4f116s2      4I°15/2
68  Erbium  [Xe]4f126s2      3H6
69  Thulium     [Xe]4f136s2      2F°7/2
70  Ytterbium   [Xe]4f146s2      1S0
71  Lutetium    [Xe]4f145d6s2    2D3/2
72  Hafnium     [Xe]4f145d26s2   3F2
73  Tantalum    [Xe]4f145d36s2   4F3/2
74  Tungsten    [Xe]4f145d46s2   5D0
75  Rhenium     [Xe]4f145d56s2   6S5/2
76  Osmium  [Xe]4f145d66s2   5D4
77  Iridium     [Xe]4f145d76s2   4F9/2
78  Platinum    [Xe]4f145d96s    3D3
79  Gold    [Xe]4f145d106s   2S1/2
80  Mercury     [Xe]4f145d106s2      1S0
81  Thallium    [Hg]6p   2P°1/2
82  Lead    [Hg]6p2      3P0
83  Bismuth     [Hg]6p3      4S°3/2
84  Polonium    [Hg]6p4      3P2
85  Astatine    [Hg]6p5      2P°3/2
86  Radon   [Hg]6p6      1S0
87  Francium    [Rn]7s   2S1/2
88  Radium  [Rn]7s2      1S0
89  Actinium    [Rn]6d7s2    2D3/2
90  Thorium     [Rn]6d27s2   3F2
91  Protactinium    [Rn]5f26d7s2     4K11/2
92  Uranium     [Rn]5f36d7s2     5L°6
93  Neptunium   [Rn]5f46d7s2     6L11/2
94  Plutonium   [Rn]5f67s2   7F0
95  Americium   [Rn]5f77s2   8S°7/2
96  Curium  [Rn]5f76d7s2     9D°2
97  Berkelium   [Rn]5f97s2   6H°15/2
98  Californium     [Rn]5f107s2      5I8
99  Einsteinium     [Rn]5f117s2      4I°15/2
100     Fermium     [Rn]5f127s2      3H6
101     Mendelevium     [Rn]5f137s2      2F°7/2
102     Nobelium    [Rn]5f147s2      1S0
103     Lawrencium  [Rn]5f147s27p    2P°1/2
104     Rutherfordium   [Rn]5f146d27s2   3F2
105     Dubnium     [Rn]5f146d37s2   4F3/2
106     Seaborgium  [Rn]5f146d47s2   0
107     Bohrium     [Rn]5f146d57s2   5/2
108     Hassium     [Rn]5f146d67s2   4
