Europium Ionization Energy

The Europium Ionization Energy is the energy required to remove from atom one mole of electrons with subsequent production of positively charged ion of Europium.
Eu -> Eu⁺ + e^-
This process can be repeated many times, but the energy cost is increased dramatically. The general equation for the Europium is:
Eu^N+ -> Eu^(N+1)+ + e^-

Eu -> Eu¹⁺ = 546.7 kJ/mol = 130.79 Kcal/mol
Eu¹⁺ -> Eu²⁺ = 1085 kJ/mol = 259.57 Kcal/mol
Eu²⁺ -> Eu³⁺ = 2404 kJ/mol = 575.12 Kcal/mol
Eu³⁺ -> Eu⁴⁺ = 4110 kJ/mol = 983.25 Kcal/mol