Why water is life

(Photo by Dion Ogust)

Your brain is mostly made of it. So are your eyes. Thus, the present situation is basically water reading about water. It has been six years since we last explored this magical substance, so let’s take a deeper look.

It’s hard not to appreciate H2O, despite it being the most common compound in the cosmos. Usually it takes the form of ice or gas, arrayed beautifully. The rings of Saturn are countless ice chunks. Comet tails are mostly water vapor. Most stars are surrounded by steam.

Here on Earth, it mostly shows its rarest phase: liquid. Gaseous water never “shows itself” at all, because it’s invisible. Clouds? They’re not vapor, but countless liquid drops – typically a million pounds’ worth of it. Teakettle vapor? No, you never see steam when you make tea. The two-inch transparent gap between a teapot’s spout and the white “steam”: that’s the actual gaseous H2O. The white stuff popularly called “steam” is where tiny liquid droplets are condensing.


The water phase only exists in an extremely slender 180-degree temperature range, compared with the 482 degrees within which it exists as ice, and the thousands of degrees as vapor. And even that meager temperature band is not enough; the H2O must also be under pressure, supplied on this planet by our atmosphere’s weight. Only then do you experience liquidy magic.

Next time you hold a glass of water, consider: Two-thirds of its contents are pure hydrogen, just like most of the universe. The glass’ other component, oxygen, is so much heavier than hydrogen (atom-by-atom, oxygen is 16 times more massive) that, even though there are twice as many hydrogen as oxygen atoms in water, seven-eighths of water’s weight is oxygen. Since your body is mostly water, two-thirds of your own weight is pure oxygen. So are other animals, and solar system bodies, too. When coyotes howl at the Harvest Moon, it’s basically oxygen howling at oxygen.

Water’s strangest characteristic is this: The two hydrogen atoms chemically bonded to one oxygen atom that comprise water are not linked in a straight line (180 degrees), but at an angle of 105 degrees. This fact alone has made life on Earth possible, and perhaps on countless other worlds as well.

The odd 105-degree angle gives the oxygen portion a more negative attraction and the hydrogen portion a more positive attraction. This results in water molecules aligning themselves. The oxygen of one bonds to the hydrogen of the next in a network of weak connections. So, instead of being a loose mixture of individual floating molecules, water is a latticework that behaves like a much-bigger structure.

This little feature has tremendous significance: Without such hydrogen bonding, water would be like all the other molecules of its size and weight: like natural gas, a vapor at room temperature. This odd electrical hydrogen bonding is why your veins and brains are filled with fluid instead of gas.

The topic arises because now, in late October, we’re about to say goodbye to rain and enter the half-year when we deal with frozen water. The biggest negative consequence is that liquid runs off on its own, while snow and ice stay put and pile up. And, while there will soon be more H2O on the ground, there’s oddly less in the atmosphere. Since cold air can hold just one-thirtieth as much water vapor as very warm air, the substance we breathe is becoming desiccated. Even in our homes, the average relative humidity is now shifting from around 55 percent to less than 25 percent – often even 15 percent. This is bad for furniture, can cause a guitar soundboard to crack and can make noses and bronchial areas susceptible to viral attacks.

We never escape the consequences of being water creatures.

Want to know more? To read Bob’s previous columns, click here. Check out Bob’s podcast, Astounding Universe, co-hosted by Pulse of the Planet’s Jim Metzner.