What are the differences between polar …

Polarity simply means the separation of positive and negative charge. Polar compounds are those which possess a dipole. A dipole is a system of equal and opposite charges separated by a small distance.

In simple terms, polar compounds are those compounds in which there is separation of positive and negative charge due to difference in the electron attracting power or electronegativity of the two atoms. Thus ionic compounds would always be polar compounds in which there is one positively charged species and one negatively charged species present. You can very well make out that the positive and negative charges are separated from each other.

Now consider covalent molecules. In covalent molecules like HCl, Chlorine is more electronegative than hydrogen. Hence it will attract the shared pair of electron between hydrogen and chlorine towards itself. When one atom attracts the shared pair of electrons in the covalent bond towards itself, it acquires a slight negative charge and the other atom acquires a slight positive charge. Thus here, there is partial separation of positive and the negative charge. This leads to development of slight ionic character in the covalent compound, making them polar.

Non-polar molecules are those in which there is no separation of charge and it is symmetrically distributed in the molecule. Thus the main difference between polar and non-polar molecules lies in the separation of charges. In polar molecules, there is separation of positive and negative charge while in non-polar molecules there is no charge separation. Example of non-polar molecule includes CH4. There is not much electronegativity difference between carbon and hydrogen, as a result of which the bonding electrons are equally shared between carbon and hydrogen. So there is no development of positive and negative charge.