NCERT · Class 10 · Science · Metals and Non-metalsShow the formation of magnesium chloride ($MgCl2$) by the transfer of electrons between magnesium and chlorine atoms. Why do ionic compounds have high melting points?

Formation of Magnesium Chloride ($MgCl_2$): Magnesium ($Mg$) has an atomic number of 12 and an electronic configuration of 2, 8, 2. It loses 2 valence electrons to achieve a stable octet, forming a magnesium cation ($Mg^{2+}$): $$Mg \rightarrow Mg^{2+} + 2e^-$$

Chlorine ($Cl$) has an atomic number of 17 and an electronic configuration of 2, 8, 7. Each chlorine atom gains 1 electron to complete its octet, forming a chloride anion ($Cl^-$): $$2Cl + 2e^- \rightarrow 2Cl^-$$

Transfer of electrons leads to the ionic compound: $$Mg^{2+} + 2Cl^- \rightarrow MgCl_2$$

Reason for High Melting Points: Ionic compounds are composed of oppositely charged ions bound together by extremely strong electrostatic forces of attraction in a solid crystalline lattice. A significant amount of heat energy is required to break these powerful inter-ionic forces. Consequently, ionic compounds possess high melting points.