Water molecule is formed by two hydrogen atoms that are covalently bonded with an oxygen atom. In a covalent bond, the electrons are shared equally between the two bonding atoms. But this is not the case with water molecule. In the water molecule, the electron pair is strongly attracted by oxygen than hydrogen. This pull of the electrons by oxygen atom gives an asymmetrical distribution of charge. This asymmetry leaves the molecules with a partial negative charge (δ-) and partial positive charge (δ+). This partial charge of molecules is known as polarity. This property of polarity helps other molecules to dissolve easily in water.