Question

Explain BeCl2 has 0 dipole moment although the Be-Cl bonds are polar?

Answer 1

The molecule with symmetrical & linear geometries have zero dipole moment because they  are vector in nature & the dipole of different bonds cancel with one another & in a unsymmetrical molecule & bent geometries, the geometries have specific dipole moment because the bond polarities do not cancel each other.

The Lewis structure for BeH2 is as follows:

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

Answer 2

Answer: Because the polarities cancel each other.

Explanation : Formula used  for calculating hybridization

$:{\text{Number of electrons}} =\frac{1}{2}[V+N-C+A]$

where, V = number of valence electrons present in central atom i.e. beryllium= 2

N = number of monovalent atoms bonded to central atom=2

C = charge of cation = 0

A = charge of anion = 0

$BeCl_2:$

${\text{Number of electrons}} =\frac{1}{2}[2+2-0+0]=2$

The number of electrons is 2 that means the hybridization will be $sp$ and the electronic geometry of the molecule will be linear.

The electronegativity of chlorine is greater than beryllium and thus both the bonds are polar but as the shape is linear, the polarities cancel each other as they are equal and opposite and the molecule becomes non polar.