The problem
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.
To name the polyatomic ions in the given problem, you can use a reference source like the link you provided: http://antoine.frostburg.edu/chem/senese/101/compounds/polyatomic.shtml#novices
1) HCO3- is called "bicarbonate" or "hydrogen carbonate."
2) NH4+ is called "ammonium."
It's important to check credible sources for accurate and up-to-date information on polyatomic ion names.