Question

(c) Element X is a metal with a valency 2, Y is a non-metal with a valency 3.
(i) Write an equation to show how Y forms an ion?
(ii) If Y is a diatomic gas, write an equation for the direct combination of X and Y to form a compound.

Answer 1

Part 1: Formation of ion:-

• We know that a metal loses its electron to form a cation, but a non-metal gains electrons in order to form an anion.
• As it is given that the valency of Y is 3, hence the equation of formation of ion is as follows: $\mathrm{Y}+3{\mathrm{e}}^{-}\to {\mathrm{Y}}^{3-}$
• Here Y gains 3 electrons in order to form ${\mathrm{Y}}^{3-}$anion.

Part 2: Formation of compound:-

• X has a valency of 2 and Y has a valency of 3. Y is given as diatomic.
• Hence reaction equation is-$\mathrm{X}+{\mathrm{Y}}_2\left(\mathrm{g}\right)\to {\mathrm{X}}_3{\mathrm{Y}}_2$
• But this equation is not balanced, so we need to balance it- $6\mathrm{X}+2{\mathrm{Y}}_2\left(\mathrm{g}\right)\to 2{\mathrm{X}}_2{\mathrm{Y}}_3$
• Now, this equation is balanced.

Final answer:-

(i) Equation of formation of ion - $\mathrm{Y}+3{\mathrm{e}}^{-}\to {\mathrm{Y}}^{3-}$

(ii) Formation of compound- $6\mathrm{X}+2{\mathrm{Y}}_2\left(\mathrm{g}\right)\to 2{\mathrm{X}}_2{\mathrm{Y}}_3$