Help! Possible names and Z Numbers?

Question

Question:
The first six ionization energy for the elements X Y are shown in the element table below. Identify possible names or Z numbers for the elements X and Y? (Note: the ionization energy is not given!)

Table:
http://img130.imageshack.us/img130/5373/tablezy8.png

Answer 1

As you can seen the first 4 ionization energies increases slightly then there is a jump.This means that X and Y have 4 valences >> group IVA
X has higter ionization energies so X is over Y in the group.
I thing X is C and Y is Si

Answer 2

X is a Gr 1 (Alkali) and Y is a Group 3 or Aluminium group metal.