JAMB Chemistry 2023 Paper

Concept:An electrovalent (ionic) bond is formed by the complete transfer of electrons from one atom to another, usually between a metal and a non-metal.Explanation:Sodium chloride ($\mathrm{NaCl}$) is a typical electrovalent compound.Sodium ($\mathrm{Na}$) is a metal with one valence electron.Chlorine ($\mathrm{Cl}$) is a non-metal with seven valence electrons.Sodium donates its single valence electron to chlorine.This transfer produces a sodium ion ($\mathrm{Na}^+$) and a chloride ion ($\mathrm{Cl}^-$).The oppositely charged ions are held together by strong electrostatic forces of attraction.This electrostatic attraction is called an electrovalent or ionic bond.The other compounds listed contain covalent bonds.Carbon dioxide ($\mathrm{CO}_2$), water ($\mathrm{H}_2\mathrm{O}$), and methane ($\mathrm{CH}_4$) all share electrons between atoms rather than transferring them completely.Answer:A. $\mathrm{NaCl}$ (sodium chloride) is the example of an electrovalent bond.