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. 

Answer 2

the structue of BeH2

  H - Be - H

The bond are polar but the dipole moment e]which is developed towards one hydrogen is cancelled by other and so it dipole moment become zero