Roentgenium Ionization Energy

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

There is no data about Roentgenium ionization energy