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

The Lewis structure for BeH2 is as follows:


H:Be:H


Here there is no lone pair at the central atom (Be) and there are two bond pairs on either side. Hence, BeH2 is of the type AB2 having linear structure.



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


22