* Magnesium (Mg): A silvery-white alkaline earth metal.

* Carbon (C): A nonmetal that forms the basis of organic compounds.

* Oxygen (O): A highly reactive nonmetal that is essential for life.

In a single molecule of magnesium carbonate, these elements are present in the following proportions:

* 1 Magnesium atom (Mg)

* 1 Carbon atom (C)

* 3 Oxygen atoms (O)

Therefore, the chemical formula of magnesium carbonate is MgCO₃.