Question

Explain why BeH₂ molecule has a zero dipole moment although the Be–H bonds are polar.

Answer 1

The Lewis structure for BeH₂ is as follows:

There is no lone pair at the central atom (Be) and there are two bond pairs. Hence, BeH₂ is of the type AB₂. It has a linear structure.

Dipole moments of each H–Be bond are equal and are in opposite directions. Therefore, they nullify each other. Hence, BeH₂ molecule has zero dipole moment.