What is the chemical formula for calcium oxide?

1 Answer
Nov 6, 2014

The formula for calcium oxide is CaO.

Explanation:

Calcium oxide is an ionic compound composed of the metal calcium and nonmetal oxygen.

Calcium is an alkali earth metal (group 2/IIA). The atoms of the alkali earth metals have two valence electrons, which they lose when forming ions. Therefore, calcium cations have a charge of 2^+.

Oxygen is in group 16/VIA and the atoms of all elements in this group have six valence electrons, and need two more to have an octet and become stable. Therefore, oxide anions have a charge of 2^(-).

The overall charge of an ionic compound is zero. Since the charges of the calcium and oxide ions are equal but opposite, the calcium and oxide ions form a 1:1 ratio (2^+ + 2^(-)=0), and the chemical formula is "CaO".

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