Ionization Energy Calculator
Look up ionization energies and explore how energy requirements change with successive electron removal.
Na
Sodium
IE1 (Ionization #1)
Na(g) → Na⁺(g) + e⁻
Ionization Energy:
496 kJ/mol
kJ/mol
496
eV
5.14
kcal/mol
118.5
All Ionization Energies
IE1: 496
IE2: 4,562
IE3: 6,910
IE4: 9,543
IE5: 13,354
IE6: 16,613
IE7: 20,117
IE8: 25,496
Cumulative energy to remove 1 electron(s): 496 kJ/mol
About Ionization Energy
Ionization energy is the energy required to remove an electron from a gaseous atom or ion. Successive ionization energies increase because you're removing electrons from increasingly positive ions. Large jumps in IE indicate removal of core electrons after the valence shell is empty.