what is the chemical formula for calcium
Report Abuse. Calcium is an element with an ion charge/oxidation number of 2+. Carbonate is a polyatomic ion with an ion charge of 2-. Since the two ion charges cancel out or equal zero, the formula would be CaCO3(the three is a subscript.) the Ca is the symbol for Calcium and the formula for carbonate is CO3.blah Â· 9 years ago.Thumbs up.arbonate is a polyatomic ion with an ion charge of 2-. Since the two ion charges cancel out or equal zero, the formula would be CaCO3(the three is a subscript.) the Ca is the symbol for Calcium and the formula for carbonate is CO3. blah Â· 9 years ago. Thumbs up.