Identify the group number of the element

Question

Identify the group number of the element that has the following successive ionization energies (in kJ/mol). 

IE₁ = 577        IE₂ = 1,816     IE₃ = 2,881   IE₄ = 11,600   

IE₅ = 14,800     IE₆ = 18,400     IE₇ = 23,300

Answer 1

These are the successive ionization energies of aluminum, which is Group 13 or IIIA, depending on how you're taught to number the groups. The way you could know this is these data are clearly for an atom with 3 valence electrons. Going from the third to the fourth ionization energy is a huge increase in energy, meaning the third is the removal of a valence electron (to form the stable Al3+) and the fourth is the removal of a core electron (forming the unstable Al⁴⁺).