Solving Nature of Atoms Homework: Part (a) ionization energy Z=2

[arod2812]

Homework Statement

(a) What is the minimum energy (in electron volts) that is required to remove the electron from the ground state of an ionized atom (Z=2)? (b) What is the ionization energy for this ion?

Homework Equations

After doing what I got the answer for part (b)... but I don't know what part (a) requires. I thought this number would be 13.6 eV, but it's not. What exactly is part (a) asking?

The Attempt at a Solution

I used the equation E= -13.6*(Z^2/n^2). I plugged in 2 for Z and 1 for n.

 

[Astronuc]

13.6 eV is the ionization of atomic hydrogen. In ionziation, the electron is completely removed as opposed to simply moved up to an excited state in the atom.

Z=2 is of course He.

See - http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html - for hydrogen

http://hyperphysics.phy-astr.gsu.edu/hbase/atomic/grotrian.html
http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/helium.html