# How to find the Ionization energy of He+

1. Sep 21, 2008

Ok so I'm using the equation E= (-Z^2 x Rh)/ n^2
RH is a constant of 2.178x10^-18

I determined that the second ionization energy of He is the ionization energy of He+.

If my math is right, the ionization energy is 8.712x10^-18... this is assuming n=1, as I've determined it from ground state... But it that the ionization energy of He+?

2. Sep 22, 2008

### granpa

according to 'kalzium', a linux program which is basically a periodic table of the elements with all sorts of chemical data for each element, the experimentally determined ionization energies of helium (which you can look up for yourself on the internet) are:
24.587 ev
54.417 ev

obviously this isnt 'giving you the answer' since I doubt these will agree with your equation but they may give you a number to check your answer against. if your number is very different then its probably wrong. just use google to convert the units.

I would be floored if the 2 numbers are exactly the same.