The problem

Question

How many electrons does the netural atom gain or lose to form each of the following ions?
1)Ca2+
2)I-

The answer is contained in the question. If there is a "+", elecrons are lost. If there is a "-", electrons are gained. The number gained or lost equals the ion charge. The charge of I- is minus 1.

okay thanks.. one more question

the problem
Write the name of the following polyatomic ions.
1)HCO3-
2)NH4+

http://antoine.frostburg.edu/chem/senese/101/compounds/polyatomic.shtml#novices

Memorize these quickly.