Why HCl is polar whereas $C{{l}_{2}}$ molecule is non-polar?

In $C{{l}_{2}}$ both atoms have same electronegativity. Hence the shared pair of electrons is attracted equally by both and remains exactly in the centre. No end acquires negative or positive charge. In HQ, chlorine is more electronegative than H. Hence shared pair of electrons is more attracted towards chlorine, which, therefore acquires nega-tive charge while H acquires positive charge.