Explanation:
Atomic number of magnesium is 12 and its electronic configuration is 2, 8, 2. So, to acquire stability it loses 2 valence electrons and hence forms [tex]Mg^{2+}[/tex] ion.
Whereas atomic number of fluorine is 9 and its electronic distribution is 2, 7. And, to attain stability its needs to gain one electron and hence then it forms [tex]F^{-}[/tex] ion.
Therefore, when both magnesium and fluorine chemically combine together then magnesium atom will donate its 2 valence electrons to the fluorine atom.
Hence, they will tend to form magnesium fluoride, that is, [tex]MgF_{2}[/tex].
