The Importance of Water as a Medium for Life

659 Words2 Pages

Water is a very important liquid found on the Earth's surface and

makes up 60 to 90 % of the fresh mass of all living things and is very

important for cells. It is also an important habitat for animals such

as fish and other aquatic organisms. It consists of 2 hydrogen atoms,

covalently bonded to an oxygen atom. When discussing what makes water

such an important medium for life, I must consider properties, such as

its dipolar charge, its ability as a solvent, its thermal properties,

its density, its high surface tension and its cohesion.

An important feature of water is that it has a dipolar (uneven)

charge. This occurs because of the covalent bonds shared between the 2

hydrogens and the oxygen atoms. When these covalent bonds are formed,

the oxygen nucleus attracts electrons more then the hydrogen nuclei

do, due to oxygen having 8 protons opposed to hydrogen's 1 proton. The

result of this is that oxygen has a slight negative charge (δ-), and

hydrogen having a slight positive charge (δ+).

Water is an excellent solvent and has an ability to dissolve many

polar substances in it. This is caused by water molecules (dipolar

molecules) being attracted to polar molecules, surrounding them and

separating them, making them dissolve. These dissolved chemicals are

then free to move around and can then react with other chemicals. It

is for this reason that biochemical reactions occur so effectively in

living organisms, since living cells have a cytoplasm based in

solution.

Water molecules are attracted to one another by hydrogen bonds,

restricting the movement of the particles. It is for this reason that

water requires a relatively large quantity of energy to increase its

temperature. Consequently, water is slow to change temperature in

areas of high water content. This is useful in living organisms as it

makes keeping a stable body temperature easier, being able to avoid

rapid temperature changes and helping reactions in the body to take

place at a narrow range in temperature. Another benefit of water's

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