On which side of the periodic table would you find an element whose atom is likely to form a cation? Which atom property is related to this question?

Ans: is it the right side of the periodic table that you would find the elements whose atom are likely to form a cation, since Al becomes Al3+ oxygen becomes O2+.

however what does it mean by the second part of the question, which atom property is it related to, is it the first ionization energy.

Please check and explain.