Structure of Water

Main Idea:

A water molecule is polar, because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.

For this reason, water has been called the universal solvent.

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It can be quite correctly argued that life exists on Earth because of the abundant liquid water. Other planets have water, but they either have it as a gas (Venus) or ice (Mars). Recent studies of Mars reveal the presence sometime in the past of running fluid, possibly water. The chemical nature of water is thus one we must examine as it permeates living systems: water is a universal solvent, and can be too much of a good thing for some cells to deal with.

Water is polar covalently bonded within the molecule. This unequal sharing of the electrons results in a slightly positive and a slightly negative side of the molecule. Other molecules, such as Ethane, are nonpolar, having neither a positive nor a negative side.

These link up by the hydrogen bond discussed earlier. Consequently, water has a great interconnectivity of individual molecules, which is caused by the individually weak hydrogen bonds, that can be quite strong when taken by the billions.

Water has been referred to as the universal solvent. Living things are composed of atoms and molecules within aqueous solutions (solutions that have materials dissolved in water). Solutions are uniform mixtures of the molecules of two or more substances. The solvent is usually the substance present in the greatest amount (and is usually also a liquid). The substances of lesser amounts are the solutes.