Question

How do you write a balanced equation for the combination of magnesium and oxygen to form magnesium oxide, MgO?

Answer 1

Hint: A balanced chemical equation tells us the exact number of atoms on the reactants and that of the products side. The combination reaction consists of a reaction between two species to form one product. The given reaction is magnesium with oxygen. The balancing will require writing the same number of moles of reactants and products.

Complete answer:
A chemical reaction is the process where there is some change in chemical composition. A chemical reaction can be expressed in the form of a balanced chemical equation. A balanced chemical equation consists of the same amount of reactants and the products. This consists of the same number of moles on the reactant and the product side.
A chemical equation is balanced by balancing the charges on the atoms that form a molecule; the charges should be the same at the reactant as well as the product's side. We have been given a combination reaction between magnesium and oxygen that forms magnesium oxide, the reaction may be:
$Mg+{{O}_{2}}\to MgO$
Here, we have oxygen in molecular form that is dioxygen, but magnesium is 1 atom. The charge of magnesium is +2 while that of oxygen is -2. In the reactant side, O has -4 charges, in the products side it has -2, so adding 2 with MgO and with Mg will balance the atoms as well as the charges. So, a balanced chemical equation is obtained as:
$2Mg+{{O}_{2}}\to 2MgO$
So, a balanced equation for the combination of magnesium and oxygen to form magnesium oxide, MgO is $2Mg+{{O}_{2}}\to 2MgO$.

Note:
The reaction here is the combination reaction. This reaction practically happens when a magnesium ribbon is burnt in air, which is a combustion reaction, which results in the formation of magnesium oxide. The charge on the atoms is also called their oxidation state that tells the ability to lose or gain electrons.