In Galveston, we are always aware of water — we are literally surrounded by it.
Water is the most abundant substance on earth.
For starters, it covers three quarters of the earth’s surface and makes up 60 percent of the human body.
Any one of us would have trouble surviving even one week without water.
Water is important, abundant (but not always pure) and unique.
It is this uniqueness that I would like to address in this column.
Water is two molecules of hydrogen bonded to one molecule of oxygen and is one of the most stable substances known.
Pure water is essentially tasteless, odorless and colorless.
That is amazing to me.
It’s sort of like water is our baseline for all tastes, odors and colors because it has zero of each.
Water is the only substance which exists in large amounts as a gas, liquid and solid at normal temperatures found on the earth’s surface.
We are all familiar with liquid water, ice and water vapor — we call water vapor humidity in Galveston.
Based solely on its constituent atoms (hydrogen and oxygen), water (at atomic weight 18) should only exist as a gas at normal temperatures.
Other substances made up of much heavier atoms are found only as gases at normal temperatures.
Why is this?
Without getting too technical, each water molecule has distinct positive and negative ends — like a magnet.
This causes water molecules to tend to stick together — negative to positive ends.
These hydrogen bonds, as they are called, hold the water molecules together and allow water to exist as a liquid at much higher temperatures than would be expected.
Thus we can have sea ice, oceans of liquid water below this ice and clouds of water vapor above it.
Water is one of the very few known liquids which expands when it freezes.
You may say “so what,” or even “I wish it didn’t because that causes water pipes to burst.”
However, the expansion of water upon freezing causes ice to float on liquid water.
If, instead, like almost all liquids, water contracted upon freezing, oceans and lakes would freeze from the bottom up and become solid ice when the air temperature was below freezing for a long enough period.
As it is, ice floats and insulates the water below from the cooler air, allowing marine life to survive in the liquid water below — even at extremely cold air temperatures.
These are just some of the truly unique properties of water.
Water is without a doubt a wonderful substance, and isn’t it amazing that we (yes, all life on earth) absolutely need all of water’s uniqueness to even exist?
Joe Concienne of Galveston, a chemical engineer who spent much of his career in Texas City, writes an occasional column on the basic concepts of science. He can be reached at email@example.com.