In ice each water molecule is hydrogen bonded to 4 other neighbouring water molecules to form ice crystal. This arrangement is necessary to ensure the strongest degree of H−bonding in a uniform, extended crystal lattice resulting in greater openers of the ice structure. In liquid water, each molecules is H−bonded to approximately 3.4 other water molecules. These H−bonds are constantly being formed and breaking up because of rapid thermal motions of molecules but in ice hydrogen bonds are stable.