How can i differentiate between a molecule being polar and non-polar?
You can differentiate between polar and non polar molecules by means of dipole moment. Dipole moment is produced when two atoms having larger difference of electronegativity are bonded together. Polarity of molecule can be determined by net dipole moment . Dipole moment is vector quantity therefore when all dipole moments cancel each other then net dipole moment is zero and molecule is non polar. For example CO2 is non polar because there are two equal dipole moments which are exactly in opposite directions. Both dipole moments will cancel each other and net dipole moment will be zero. That’s why CO2 is non polar. Now take an another of carbontetrachloride CCl4. This molecule is tetrahedral and there are 4 equal dipole moments in this molecule. Since this molecule is symmetrical, all dipole moments will cancel each other and net dipole moment will be zero. You can confirm this result by drawing vectors on each bond of molecule. All the vectors are equal and are separated by equal angle
