HYDROGEN BONDING Whenever a hydrogen atom is bonded to a highly electronegative atom (like nitrogen, oxygen, or fluorine), this will form a highly polar bond. The electronegative atom takes on a negative partial charge and the hydrogen atom takes on a partial positive charge. This is what happens between polar covalent molecules but happens to a greater degree with hydrogen bonding. Hydrogen bonding is found extensively with water . The hydrogen atoms bind to the oxygen atom in a polar covalent bond; however, the hydrogen atoms between two different molecules in a solution of water are also involved in hydrogen bonding. This is partially why water has the polar properties it has. This bonding affects the crystalline structure of ice, which creates a hexagonal lattice shape. Figure 27 shows the basic structure of water in its various states:
Figure 27.
The hexagonal structure of ice makes ice less dense than liquid water so that water as a solid actually floats on the surface of water instead of sinking, which is the case with nonpolar molecules that form a solid shape at lower temperatures. It is also the
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