Question

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

Answer 1

The Lewis structure for BeH molecule is as follows:

H:Be:H :- 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 Be – H bond are equal and opposite in direction. Therefore, they nullify each other. Hence, BeH₂ has a net zero dipole moment.