Terbium Ionization Energy

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

Tb -> Tb¹⁺ = 564.6 kJ/mol = 135.07 Kcal/mol
Tb¹⁺ -> Tb²⁺ = 1112 kJ/mol = 266.03 Kcal/mol
Tb²⁺ -> Tb³⁺ = 2114 kJ/mol = 505.74 Kcal/mol
Tb³⁺ -> Tb⁴⁺ = 3839 kJ/mol = 918.42 Kcal/mol