Group I periodic table reaction with Cl2, Group II reaction with Cl2, and Group I reaction with Br2?

Take a IIa element, Ca. To get to an octet, it has to lose two electrons. To get to an octet, each chlorine will need to accept one electron. So CaCl2 is the compound that would form. The calcium has lost two electrons, and the two chlorine's have each accepted one electron. And the compound formed is ionic in nature.