The hydrogen-bond lattice causes water to have an unusually high specific heat, an unusually high heat of vaporization and an unusually low density in solid form. This is because of the so called "hydrogen bonding". Water molecule consist of Hydrogen and Oxygen molecule which has large electronegativity difference, which arise polarity between O-H bond, thus increasing the efficiency of hydrogen from both oxygen as well as Hydrogen ends. When we give heat to H2O water molecule, some heat first use to break the weak hydrogen bonds which increases the specific heat. Because of Hydrogen bonding, the molecules network goes on increasing which account for high melting point and boiling point. On heating liquid, Hydrogen gets converted into steam and it has high heat of vaporisation because heat given to water in liquid state first utilizes in breaking the H-bonds
