Question

In which of the following species are the bonds non-directional?

• A. $NC{l}_3$
• B. $RbCl$
• C. $BeC{l}_2$
• D. $BC{l}_3$

Answer 1

The correct option is B $RbCl$

Ionic bonds are the electrostatic force of attraction between the cations (positively charged ions) and the anions ( negatively charged ions). The force of attraction is uniform in all directions and thus making the bonds non-directional. Covalent bonds are formed by the overlapping of orbitals, which can occur either by axial overlap or lateral overlap. Thus, covalent bonds are directional in nature.

a) $NC{l}_3$: Nitrogen and chlorine are both non-metals and therefore $NC{l}_3$ is a covalent compound.

b) $RbCl$: Rubidium is a metal and chlorine is a nonmetal and therefore $RbCl$ is an ionic compound.

c) $BeC{l}_2$: Though beryllium is a metal and chlorine is a non-metal, it does not form an ionic compound as the electronegativity difference is less than 1.7. Also, due to the smaller size of Be, it has high polarising power and that accounts for significant covalent character.

d) $BC{l}_3$: Boron and chlorine are both non-metals and therefore it is a covalent compound.