Water is a very important part of our lives. Our bodies are mostly made up of water. It has a number of unique qualities. Water is a solid when it is frozen, a liquid at room temperature and a gas when it is heated up. When it is frozen, it expands.
What is water?
Atoms are the smallest components of an element. Atoms join to create molecules. Water contains three molecules. There are two hydrogen atoms and one oxygen atom in every molecule of water. Each drop of water has billions of water molecules in it. Pure water has no taste, odor or color. It is found as a solid, liquid or a gas. Liquid water is very common. It is what we drink and wash in. liquid water is a universal solvent. This means that anything water-soluble can be dissolved in water. When water becomes a gas, you cannot see it. Boiling water will turn liquid water into a gas called water vapor. When the water vapor cools it becomes visible and is called steam. The clouds in the sky are made up of water vapor that is visible like the steam is. Steam forms at 212 degrees Fahrenheit and 100 degrees Celsius. When the water vapor surrounds a piece of dust in the air, it becomes heavier and forms raindrops or snow. These fall to the earth as liquid, or solid in the case of snow.
Why does water expand when it freezes?
When water freezes, the molecules move farther from each other. This means that the ice is less dense than the liquid water. This is why an ice cube will float in a glass of water. The less dense ice contains the same amount of molecules as the liquid water did, and that is why it expands and takes up more room. The molecules are the same but the space between them is greater. Water freezes at 32 degrees Fahrenheit or 0 degrees Celsius. Water expands about nine percent when it freezes. This is caused by the structure of the water molecule. The hydrogen atom in the water molecule forms bonds between the oxygen atoms. The hydrogen bond becomes stronger when the temperature lowers. When water turns to ice and becomes solid, the hydrogen bonds are completely locked in an open shape. This forms a crystalline structure that is very opened up. The open structure of the ice has more space than the structure of water, with its weaker hydrogen bonds. The open structure is what makes the density of ice less than that of water and causes it to float on top of water. Because ice floats on water, many lakes and rivers only freeze on the top portion, allowing much life to exist below where water is still liquid.