Question

Elements X and Y have the following configurations:
X (2, 8, 7), Y (2, 8, 8, 2)
Answer the following questions:
(a) What will be the nature of the bond between X and Y?
(b) Draw the diagram to show the bond formation between X and Y.
(c) State three main properties of this compound.

Answer 1

(a) The nature of bond between elements X and Y will be electrovalent. Element X has seven valence electrons; that is, it needs one electron to attain a stable electronic configuration. On the other hand, element Y has two valence electrons. Hence, element Y loses two electrons and forms Y²⁺ cation and two atoms of element X take one electron each to get stabilised.

(b) The electrovalent bond formation between elements X and Y is:

$$\begin{gathered} Y\mathbf{:}\to Y^{2+}+2e^{-} \underset{\mathbf{.}\mathbf{.}}{\overset{\mathbf{.}\mathbf{.}}{\mathbf{:}\mathrm{X}·}}+e^{-}\to {\left[\underset{\mathbf{.}\mathbf{.}}{\overset{\mathbf{.}\mathbf{.}}{\mathbf{:}X\mathbf{:}}}\right]}^{-} \\ {Y}^{2+}+2{\left[\underset{\mathbf{.}\mathbf{.}}{\overset{\mathbf{.}\mathbf{.}}{\mathbf{:}X\mathbf{:}}}\right]}^{-}\to Y{X}_2 \end{gathered}$$

(c) Disclaimer: Any three properties of the compound can be mentioned in the answer.
The compound formed is ionic. The properties of ionic compounds are:

(1) They have high melting and boiling points.

(2) They are soluble in water (polar solvents).

(3) They release free ions in the solution.

(4) They are good conductors of electricity in molten or aqueous state.