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Several times a day, your body takes in a chemical called hydrogen oxide.
This chemical can eat away solid rock over time. When frozen, it can crack concrete! It can also destroy the cells of plants and animals.
Hydrogen oxide is water’s chemical name. The symbol is so familiar that it is used as a nickname: H2O. The H stands for an atom of hydrogen. The 2 means there are two hydrogen atoms. The O stands for an atom of oxygen. So, water is a bond between three atoms: two positively (+) charged hydrogen atoms and a negatively (-) charged oxygen atom—H-O-H. That is true whether the water is a liquid, solid (ice), or gas (water vapor).
Water may seem ordinary, but it has some properties that no other substance has. Water is a supersolvent! It is better at dissolving things than most other substances are. You can test many properties of water right in your own kitchen.
TRY THIS!
Rising Dome
The parts of water stick together, forming drops. The ability of these things to stick together is called cohesion. Cohesion causes water to form a “skin” on its surface. The force holding this “skin” together is called surface tension. With a straw or an eyedropper, put drops of water on a coin. Do you see a dome of water above the coin? Surface tension keeps the dome’s shape—up to a point. How many drops can you add before the dome falls and the water spills?
Breaking the Tension
Soap breaks the surface tension of water. It pulls in dirt and other particles, helping to clean dishes and other things—like you! Set a dish of water on a flat counter. Carefully put a small paper clip on top of the water’s “skin.” You might have to try it a few times to get it right. Now try to float a paper clip in a dish of soapy water. Without a “skin,” the soapy water cannot hold up the paper clip.
Supersaturated
Water, our supersolvent, dissolves salt—up to a point. What is this point? How much salt can water dissolve? Stir a teaspoon of salt into a glass of water and see how the water changes. Keep adding a teaspoon of salt and stirring until the salt no longer dissolves. The grains of salt will fall to the bottom of the glass. Let the water completely evaporate over several days. What is left in the glass?
Human Water Walker!
Can humans walk on water? Frenchman Rémy Bricka did. In 1988, he “ski-walked” across the Atlantic Ocean on special water skis. They were a little shorter than a compact car. The long skis helped to spread Bricka’s weight over the surface of the water, and that kept him from sinking. His watery hike took two months! ▶
▲ A whirlpool in the ocean is a giant version of water going down a drain. It spins tighter and tighter, and faster and faster, toward a hole in the center. Whirlpools can pull ships toward the bottom of the ocean! Then they spit the ships back up. We don’t have to worry about whirlpools near land. Ocean waves by the shore move in more random ways. They are too disorganized to form whirlpools.
▲ The wind makes waves on the ocean’s surface. Below the surface, other forces are at work. Ocean currents are strong channels of flowing water. They are caused partly by warm and cold water meeting. Warm water rises, and cold water sinks. In this satellite photo, the warm current of the Gulf Stream (red) flows up the eastern coast of the U.S. Cold currents from the Arctic (blue) flow down to meet it.
People who live in deserts or go through droughts know water is valuable. But everyone should know it’s worth saving. ▼
Worth Saving
Toilets may use as much as five gallons per flush. Newer, low-flush toilets use 3.5 gallons. But you may have to flush them more. That does not save any water and may make things worse.
