Water is essential to all life on Earth and is vital to both human survival and the survival of larger ecosystems. It also possesses unique properties. For instance, it has both a high boiling point and a high heat of vaporization, due to the high amount of energy needed to break the strong hydrogen bonds present in the compound. In addition, water exhibits high surface tension and cohesion due to the polarity present within its molecules, caused by the partial positive and partial negative charge on the hydrogen and oxygen atoms respectively, which attract each other and result in the molecules sticking together more so than most liquids. Water also has low viscosity, also known as a low resistance to flow, which is important in its role in things like blood circulation or acting as a solvent for biochemical reactions. Another property unique to water is that its solid form has a lower density than its liquid form, resulting in the phenomenon of ice floating in water.
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