[wonderkid]

i know roughly about polar.it's about uneven distributioon of charges of atoms.but i just know that.can anyone pls explain detail for me what is meant by polar and non-polar?what's the relation between polar and symmetry or non-symmetry?

[Dan]

what is meant by polar and non-polar? what's the relation between polar and symmetry or non-symmetry?

A dipole moment is an uneven distribution of charge. If a molecule has a dipole moment it is polar.

So, HCl (gas) is polar because it has a dipole moment.

However, a molecule with several polar bonds is non-polar if the dipole moments cancel out by symmetry.

For example, CO₂ is not polar. The C-O bonds are polar bonds, but because CO₂ is linear, the dipoles of the bonds exactly cancel each other out, and there is no overall  dipole moment.

Water is polar. The O-H bonds are polar, but the bent geometry of the molecule means that there is an overall dipole moment.