Free
Several times each day, your body takes in a chemical called hydrogen oxide.
It has the power to eat away solid rock over time. In its frozen state, mighty hydrogen oxide can crack concrete! It can also destroy the cells of plants and animals.
Hydrogen oxide is the chemical name for water. The chemical symbol is so familiar that it is a nickname for water: H2O. The H stands for an atom of hydrogen, which is positively charged. The 2 indicates that there are two atoms of hydrogen. The O stands for an atom of oxygen, which is negatively charged. 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 no other substance has. Water is a supersolvent! Water has the power to dissolve things like no other substance can. To find out more about what water can do, you can test many of its properties right in your own kitchen.
TRY THIS!
Rising Dome
The components of water stick together, forming drops. The ability of the components to stick together (called 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 rising above the coin? Surface tension keeps the dome intact—up to a point. How many drops can you add before the dome collapses and the water spills?
Breaking the Tension
Soap breaks the surface tension of water. Soap attracts dirt and other particles, helping to clean dishes and other items. Set a dish of water on a level counter. Carefully place a small paper clip on top of the water’s “skin.” (This will take some practice.) Then 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, and how much salt can water dissolve? Add a teaspoon of salt to a glass of water and stir it in, then look at how the water has changed. Keep adding a teaspoon of salt and stirring until the salt no longer dissolves and the grains of salt 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? Not usually, but Frenchman Rémy Bricka did. In 1988, he “ski-walked” across the Atlantic Ocean on water skis that 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 stroll took two months. ▶
▲ A whirlpool in the ocean is a giant version of water that swirls down a drain. It spins tighter and tighter, and faster and faster, toward a hole in the center. Whirlpools can pull whole ships toward the bottom of the ocean. Then they spit the ships back up. Luckily for us, ocean waves near the shore are too random for whirlpools to form.
▲ The wind creates waves on the ocean’s surface. Below the surface, though, other forces are at work. Ocean currents are strong channels of flowing water caused in part by the meeting of warm and cold water. 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 desert areas or go through droughts know water is valuable. But everyone should realize that it’s precious—and 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 more often. That does not save any water and may make the situation worse.
