JAMB Chemistry 2012 Paper

Concept:Element X with atomic number 11 and element Y with atomic number 17 are a metal and a non-metal; identify the type of bond formed by electron transfer.Explanation:X is sodium, $\mathrm{Na}$, with configuration $2,8,1$; it loses 1 electron to form $\mathrm{Na}^+$.Y is chlorine, $\mathrm{Cl}$, with configuration $2,8,7$; it gains 1 electron to form $\mathrm{Cl}^-$.The electron transfer creates oppositely charged ions held together by electrostatic attraction.Therefore, the bond formed is ionic.Answer:C. Ionic