Answer: two elements and three atoms
Explanation:
An element is the simplest substance and hence cannot be broken down using chemical reactions.
Magnesium chloride [tex](MgCl_2)[/tex] is an ionic compound formed by the transfer of electrons from element magnesium (Mg) to element chlorine (Cl) where Magmesium forms a cation [tex]Mg^{2+}[/tex] by losing two electrons and chlorine forms an anion [tex]Cl^{-}[/tex] by gaining electron.
There are 3 atoms in Magnesium chloride [tex](MgCl_2)[/tex] which include one atom of magnesium (Mg) and two atoms of chlorine (Cl).