Question

The two elements X and Y have $5$ and $7$ valence electrons respectively, what will be the formula of the compound formed by them?

• A. $XY$
• B. $X_{2}Y$
• C. $X_{3}Y$
• D. $X{Y}_3$

Answer 1

The correct option is D $X{Y}_3$

$X{Y}_3$ is formed by covalent bonding in its atoms when $X$ is short of three electrons to complete its shell while $Y$ atom is short of one electron to fill its shell. Three $Y$ atoms share its electrons with $X$ forming three $X-Y$ covalent bond. Hence, the formula of the compound formed is $X{Y}_3$.