It’s in the air you breath, the food you eat, and every living organism on Earth needs it to survive, but what is it?
Here’s how it breaks down. Water is made up of two molecules: hydrogen, which can be found in outer space, and oxygen, which so far has only been found on Earth. Together, they form what we call H2O, one oxygen atom and two hydrogen atoms. What are atoms? They’re a basic unit of matter comprised of a dense nucleolus, or center, surrounded by millions and millions of electrons in a cloud. These atoms bond with each other to form different kinds of molecules, which themselves act as building blocks for all kinds of matter. The atoms that come together to make H2O are connected by covalent bonds, which means they share pairs of electrons. But, you may ask, what are electrons? You, I’d respond, ask too many questions.
Why is Water Wet?
The old two-part quandary goes “Why is the sky blue? Why is water wet?”. Sure, it’s usually meant rhetorically, but let’s answer it anyway. The sky is blue because that’s how we perceive it. Molecules in the air scatter blue light from the sun more than they scatter red light, and we see blue light as blue because that’s how our brains interpret it to us. You could take this further and ask how do I know my blue is the same as your blue, but there’s no scientific answer to that one, and there probably never will be!
So now, why does water feel wet? It’s hard to define what interacting with water feels like without using the word wet. It’s even harder to define what wetness feels like without making some kind of reference to water. But what makes something wet? What properties does wetness have? Consider this, we’d say our hands are wet if we washed them but didn’t dry. This is because little droplets of water cling to our skin, keeping our bodies in contact with the wetting liquid. When we’re splashed, we say “Don’t get me wet!” because unlike getting “splashed” with a gaseous gust of wind, liquid water sticks to us. It does this because of adhesive forces between a liquid and a solid. We feel the impact of water splashing us because it’s a liquid, something we can readily manipulate and touch, unlike, say, oxygen. When it hits our skin, the polarized water molecules meet the non-polarized oils on our skin and begin to slide away with gravity (oil and water don’t mix!) Water is usually much warmer or much cooler than our skin temperature, so when we’re exposed to it we react to the difference. All of these things combine to give us the feeling of “wetness” when we’re exposed to water, along with other kinds of liquids.