How is hydrogen bonding among water molecules related to the structure of the water molecule?

Hydrogen bonding does not directly affect the structure of a single water molecule. It does, however, strongly influence the interactions between water molecules in a solution of water.

Hydrogen bonding is one of the strongest molecular forces second only to ionic bonding. When water molecules interact, the hydrogen bonds pull the molecules together giving water and ice distinct properties.

Hydrogen bonding is responsible for surface tension, and the crystalline structure of ice. Ice (water in its solid state) has a lower density than water, which is rare. This effect has a large impact on our biological systems and water ecosystems.