Why does a Cs atom have lower ionization energy than a Li atom?

1 Answer
Nov 29, 2015

Because the valence electron of caesium is further removed from the nuclear charge as compared to that of the lithium atom.


We are looking at the equation:

#M(g) rarrM^+(g) + e^-#

Obviously you have to pump in energy. This energy INCREASES across a Period (from left to right) and DECREASES down a Group. As nuclear charge increases, the nuclear attraction is greater. You should look at some values of this.