What are the cations and anions for the formula calcium iodide?

Calcium Iodide (##CaI_2##) separates to form one Calcium 2+ ion, ##Ca^(2+)##, and two iodine ions with a -1 charge, ##2 I^-##. The calcium ion is a cation because it carries a positive charge. The two iodine ions are anions because they carry a negative charge.

help predict which atoms will donate electrons and which will atoms receive electrons in a bond. Calcium has an oxidation number of +2. It can donate two electrons to an atom. Iodine in this situation has an oxidation state of -1. Each iodine will receive an electron from the calcium.

When calcium and 2 iodine atoms form a compound, calcium donates one electron to each iodine, giving calcium the +2 status and each iodine the -1 status.