Calculating Zeff of Cu2+

[blazinfury]

I need to calculate the effective nuclear charge of Cu2+. The formula that I am using is #protons- (total# e- - valence e-).

 

Cu config is [Ar]3d104s1

Cu2+ config is [Ar]3d9

 

So the total # of protons is 29. Total # of e- is 27 because we lost 2 due to the ionization. Now would the total number of valence e- be 17 because we are looking at the whole 3rd energy level?

 

So would the answer be 29- (27-17)= 19? Thanks.