Question

How is polarity of a "bond" different than polarity of a "molecule?" What makes a particular molecule polar versus nonpolar? based on your understanding of polarity, which of the following are polar? H2O, BeF2, CCl4, CO2, NF3.

Answer 1

n a bond if there is a difference in electronegativity between the bonded atoms then the bond is said to be polar and has dipole moment. If we choose CO2 molecule, C=O bonds are polar but it is a non-polar molecule as it is linear shaped and the dipole moment vector cancel out each other.

<---- O = C = O ---->

H2O: polar as it is V-shaped molecule and dipole moment vector does not cancel out each other.

BeF2: Non-polar as it is linear shaped molecule and dipole moment vector cancel out each other.

CCl4: Non-polar as it is tetrahedral shaped molecule and dipole moment vector cancel out each other.

CO2: Non-polar as it is linear shaped molecule and dipole moment vector cancel out each other.

NF3: polar as it is pyramidal shaped molecule and dipole moment vector does not cancel out each other.