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Ionization Energies of the Chemical Elements

Ionisation energies, ionization potentials

The ionization energy IE or free ionization enthalpy (also: ionisation energy, ionization potential) describes the energy required to remove an electron from a neutral or a partially ionized, gaseous atom or molecule (ionization):

A + IE → A+ + e-.

The energy for the separation of the first electron is called 1st ionization energy, that for the second electron is called 2nd ionization energy and that for the nth electron is called nth ionization energy.

Ionization energies are given in eV for single electrons or in kJ/mol for 1 mole = NA (Avogadro's constant) electrons (molar ionization energy); the conversion factor is:

1 electronvolt eV = 96.485307 kJ mol-1.

 

First Ionization Energies of the Chemical Elements

 

Ionization energies 1 to 5

Table with the first (IE1) to fifth (IE5) ionization energies of the chemical elements in eV.

ZSymbolElementIE1IE2IE3IE4IE5
1HHydrogen13.598433----
2HeHelium24.58738754.41776---
3LiLithium5.39171975.64122.45429--
4BeBeryllium9.322718.21114153.89661217.71865-
5BBoron8.2980225.154837.93064259.37521340.2258
6CCarbon11.260324.383347.887864.4939392.087
7NOxygen14.534129.601347.4492477.473597.8902
8ONitrogen13.6180535.121154.935577.41353113.899
9FFluorine17.422834.970862.708487.1398114.2428
10NeNeon21.5645440.9629663.4597.12126.21
11NaSodium5.139076447.2867716.20598.92138.4
12MgMagnesium7.64623515.0352780.1437109.2655141.27
13AlAluminium5.98576818.8285528.44765119.992153.825
14SiSilicon8.1516816.3458433.4932745.14215166.769
15PPhosphorus10.4866919.769530.2028851.444365.02564
16SSulfur10.3600123.3378834.7947.22272.5945
17ClChlorine12.9676323.813639.6153.465267.8
18ArArgon15.7596127.6296640.74   59.8175.02
19KPotassium4.340663331.6345.80660.9182.66
20CaCalcium6.1131611.8717250.913567.2784.5
21ScScandium6.5614912.7997724.7568573.4991.65
22TiTitanium6.8281213.575527.491943.267599.3
23VVanadium6.7461914.61829.31146.70965.2817
24CrChromium6.7665116.485730.9649.1669.46
25MnManganese7.4340215.6433.66851.272.4
26FeIron7.902416.187730.65254.875
27CoCobalt7.8810117.08433.551.379.5
28NiNickel7.639818.1688435.1954.976.06
29CuCopper7.7263820.292436.84157.3879.8
30ZnZinc9.39419917.9643939.723359.5782.6
31GaGallium5.999301620.5151530.725863.24186.01
32GeGermanium7.8994315.9346134.057645.715594.5
33AsArsenic9.788618.589228.35150.1362.63
34SeSelenium9.7523921.1930.820442.94568.3
35BrBromine11.813821.5913647.359.7
36KrKrypton13.99960524.3598436.9552.4964.69
37RbRubidium4.17712827.28983952.268.5
38SrStrontium5.6948511.0301942.8835356.27970.7
39YYttrium6.217312.22420.5260.59777
40ZrZirconium6.633913.1322.9934.3480.348
41NbNiobium6.758851425.0438.350.55
42MoMolybdenum7.0924316.1627.1346.454.49
43TcTechnetium7.2815.2629.54--
44RuRuthenium7.360516.7628.47--
45RhRhodium7.458918.0831.06--
46PdPalladium8.336919.4332.93--
47AgSilver7.5762321.4774634.83--
48CdCadmium8.9938216.9083137.48--
49InIndium5.7863618.870328.0354-
50SnTin7.3439214.632230.502640.7350272.28
51SbAntimony8.6083916.6325.344.256
52TeTellurium9.009618.627.9637.4158.75
53IIodine10.4512619.131333--
54XeXenon12.1298----
55CsCesium3.89390523.15744---
56BaBarium5.21166410.0038335.84447.0358
57LaLanthanum5.576911.05919.177449.9561.6
58CeCerium5.538710.8520.19836.75866.55
59PrPraseodymium5.47310.5521.62438.9857.53
60NdNeodymium5.52510.7222.140.4-
61PmPromethium5.58210.922.341.1-
62SmSamarium5.643711.0723.441.4-
63EuEuropium5.6703811.2524.9242.7-
64GdGadolinium6.149812.0920.6344-
65TbTerbium5.863811.5221.9139.37-
66DyDysprosium5.938911.6722.841.4-
67HoHolmium6.021511.822.8442.5-
68ErErbium6.107711.9322.7442.7-
69TmThulium6.1843112.0523.6842.7-
70YbYtterbium6.2541612.17623.0543.56-
71LuLutetium5.4258613.920.959645.2566.8
72HfHafnium6.825071523.333.33-
73TaTantalum7.54957----
74WTungsten7.98----
75ReRhenium7.83352----
76OsOsmium8.43823----
77IrIridium8.96702----
78PtPlatinum8.958818.563---
79AuGold9.2255320.2---
80HgMercury10.437518.756834.2--
81TlThallium6.10819420.428329.83--
82PbLead7.4166315.0324831.937342.3268.8
83BiBismuth7.285516.70325.5645.356
84PoPolonium8.414----
85AtAstatine9.31751(8)20294151
86RnRadon10.7485----
87FrFrancium4.072741----
88RaRadium5.2784231.014.715---
89AcActinium5.1711.75---
90ThThorium6.306711.92028.8-
91PaProtactinium5.89----
92UUranium6.194110.6---
93NpNeptunium6.2657----
94PuPlutonium6.02611.2---
95AmAmericium5.9738----
96CmCurium5.9914----
97BkBerkelium6.1979----
98CfCalifornium6.281711.8---
99EsEinsteinium6.4212---
100FmFermium6.5----
101MdMendelevium6.58----
102NoNobelium6.65----
103LrLawrencium4.963(15)14.79423.08250.867-
104RfRutherfordium6.0114.423.831.9-
105DbDubnium6.8916.0324.6534.1944.62
106SgSeaborgium7.8517.9625.7435.447.28
107BhBohrium7.717.526.637.349
108HsHassium7.618.229.337.751.2
109MtMeitnerium8.3----
110DsDarmstadtium9.9----
111RgRoentgenium10.6----
112CnCopernicium11.97----
113NhNihonium7.31----
114FlFlerovium8.62216.57634.91345.58460.606
115MsMoscovium5.57718.23427.45  448.48559.259
116LvLivermorium6.87813.77929.52639.47262.989
117TsTennessine7.63414.87122.39741.57452.591
118OgOganesson8.88816.195---

 

Ionization energies 5 to 9

Table with the sixth (IE6) to ninth (IE9) ionization energies of the elements in eV.

ZElementIE6IE7IE8IE9
1H--- 
2He----
3Li----
4Be----
5B----
6C489.99334---
7N552.0718667.046--
8O138.1197739.29871.4101 -
9F157.1651185.186953.9112 1103.1176
10Ne157.93207.2759239.0989 1195.8286
11Na172.18208.51264.25 299.867
12Mg186.76225.02265.96 328.06
13Al190.49241.76284.66 330.13
14Si205.27246.5303.54 351.12
15P220.423263.57309.6 372.13
16S88.053280.948328.74 379.55
17Cl97.03114.1958348.28 400.06
18Ar91.009124.323143.46 422.45
19K99.4117.56154.88 175.8188
20Ca108.78127.2147.24 188.54
21Sc110.68138158.1 180.03
22Ti119.53140.8170.4 192.1
23V128.13150.6173.4 205.8
24Cr90.6356160.18184.7 209.3
25Mn95.6119.204194.5 221.8
26Fe 99.1124.98 151.06233.6
27Co102128.9157.8 186.13
28Ni108133162193
29Cu103139166199
30Zn108134174203
31Ga112.7140.9169.9 210.8
32Ge115.9144.9176.4 212.7
33As127.6---
34Se81.7155.4--
35Br88.6103192.8-
36Kr78.49111125.802 231.5
37Rb82.497.43132.79 150.63
38Sr88104121.21 158.33
39Y93116129-146.2
40Zr98.46---
41Nb102.057125--
42Mo68.8276125.66143.56 164.12
43Tc----
44Ru----
45Rh----
46Pd----
47Ag----
48Cd----
49In----
50Sn----
51Sb108---
52Te70.7137--
53I----
54Xe----
55Cs----
56Ba7186101130.5
57La----
58Ce77.6---
59Pr----
60Nd----
61Pm----
62Sm----
63Eu----
64Gd----
65Tb----
66Dy----
67Ho----
68Er----
69Tm----
70Yb----
71Lu----
72Hf----
73Ta----
74W----
75Re----
76Os----
77Ir----
78Pt----
79Au----
80Hg----
81Tl----
82Pb----
83Bi88.3---
84Po----
85At----
86Rn----
87Fr----
88Ra----
89Ac----
90Th----
91Pa----
92U----
93Np----
94Pu----
95Am----
96Cm----
97Bk----
98Cf----
99Es----
100Fm----
101Md----
102No----
103Lr----
104Rf----
105Db----
106Sg59.24---
107Bh62.174.9--
108Hs6478.191.8-
109Mt----
110Ds----
111Rg----
112Cn----
113Nh----
114Fl----
115Ms----
116Lv----
117Ts----
118Og----

 

References:

[1] - Jean Sansonetti: NIST Ground Levels and Ionization Energies for the Neutral Atoms.

[2] - J. E. Sansonetti, W. C. Martin, S. L. Young: NIST Handbook of Basic Atomic Spectroscopic Data.

[3] - Darleane C. Hoffman, Diana M. Lee, Valeria Pershina:
Transactinide Elements and Future Elements.
In: The Chemistry of the Actinide and Transactinide Elements, Springer, (2006), ISBN 1402035551.

 


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Last update: 2023-05-05


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