The balanced chemical equation for the reaction of copper and oxygen to form copper oxide is:

2 Cu + O₂ → 2 CuO

Here's what it means:

* 2 Cu: Two atoms of copper (Cu) are needed as reactants.

* O₂: One molecule of oxygen gas (O₂) is needed as a reactant.

* 2 CuO: Two molecules of copper oxide (CuO) are produced as the product.

This equation is balanced because there are equal numbers of each type of atom on both sides of the equation:

* Copper (Cu): 2 on each side

* Oxygen (O): 2 on each side