Hydrogen Bonding in Water
Explains many properties of water
Key Properties of Water
spoiler: because of extensive Hydrogen Bonding
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Cohesion
Water molecules readily (and reversibly) stick together, beading up, and forming chains that move together along vessels (capillary action)
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Adhesion
Water molecules readily (and reversibly) stick to surfaces, which allows them to travel along vessels more quickly
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High Surface Tension
Water molecules join together at the surface of a body of water, forming a skin that serves as an ecological niche for some animals
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High Specific Heat
Compared to other liquids, it takes quite a lot of heat energy to raise the temperature of water by one degree Celsius. This makes water a kind of temperature buffer, both in the environment as well as in the bodies of animals which are mostly water.
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High Heat of Vaporization
When heating water, it takes extra energy to break apart molecules of water before they can vibrate quickly enough to escape as gas. Animals that sweat can cool themselves as a result of evaporative cooling, since the most energetic molecules escape.
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Ice Floats
Solid water is less dense than liquid water, which is an unusual property for matter. This means bodies of water don't freeze solid. The ice floats on the top, insulating the rest of the water from freezing, protecting the animals that live there.
Water is Essential
The Solvent of Life
Why is water essential for Life to exist on Earth? We are about 60% water - and there are some organisms that are as much as 90% water!
What is so important about water? How does it support life? There are special chemical properties of water that make it the “Solvent of Life.” Chief among these properties is the extensive Hydrogen Bonding between water molecules that make water an extremely cohesive liquid (the molecules stick together). Note that these hydrogen bonds are the intermolecular forces between different water molecules, not the intramolecular polar covalent bonds within single water molecules.
Due to the extensive hydrogen bonding, water has some emergent properties that impact life on Earth in many ways. These include: Cohesion, Adhesion, High surface tension, High specific heat, High Heat of vaporization, and the fact that ice floats (Ice is less dense as a solid than liquid water). Each of these properties determine the ways living creatures survive on Planet Earth.
What is so important about water? How does it support life? There are special chemical properties of water that make it the “Solvent of Life.” Chief among these properties is the extensive Hydrogen Bonding between water molecules that make water an extremely cohesive liquid (the molecules stick together). Note that these hydrogen bonds are the intermolecular forces between different water molecules, not the intramolecular polar covalent bonds within single water molecules.
Due to the extensive hydrogen bonding, water has some emergent properties that impact life on Earth in many ways. These include: Cohesion, Adhesion, High surface tension, High specific heat, High Heat of vaporization, and the fact that ice floats (Ice is less dense as a solid than liquid water). Each of these properties determine the ways living creatures survive on Planet Earth.
Recommended reading
The definitive text
Campbell's Biology is the standard text used in most first-year college biology courses. Reliably researched and well-written, with clear illustrations.
Related Topic
4 Types of Chemical Bonds in Biology
The bonds essential for life
