Water: States of Matter By: Cammie Goodman

Icicles, raindrops, an invisible gas in the air—these are all forms of water. Water can be a solid, a liquid, or a gas. Water can also change from one of these forms to another

States of Matter Matter is anything that takes up space and has weight Exist in different physical forms, called states. (solids, liquids, gases)

A solid is matter that keeps its own shape.

A liquid is matter that takes the shape of its container.

A gas is matter that spreads out in all directions.

Water is a kind of matter that is found in nature in all three states. Earth’s water is found in the liquid state in oceans, lakes, and rivers. Frozen water or ice is in the solid state. Frozen water is found in the polar ice caps and in large ice sheets called glaciers.

Water in its gas state is called water vapor. Water vapor is one of the gasses in the air.

Earth’s water changes state: glaciers melt, dripping water forms icicles, puddles dry up and water vapor becomes drops of dew.

Melting Melting is the change of matter from a solid to a liquid. When enough heat energy is added to the solid ice cubes, they melt. Heat makes the particles of frozen water move faster and farther apart. The solid becomes liquid water. When heat energy is added to matter, it gets hotter. Its temperature rises. Temperature is a measure of how much heat energy and object has.

Evaporation Evaporation is the change of matter from a liquid to a gas. When a liquid changes to a gas, we say it evaporates. If you heat a pot of water on a stove, the water particles start to move faster, as they move farther apart. When the temperature of the water reaches 100˚C, the water boils, or forms bubbles of gas.

Evaporation Water does have to boil to evaporate. Evaporation can happen at different temperatures, when water particles get enough heat energy. Then those particles leave the liquid water and go in the air as a gas—water vapor. Evaporation happens faster when temperatures are high. When liquid water begins to boil at 100˚C, it evaporates quickly.

You may see a cloud of “steam” rising from a pot of boiling water You may see a cloud of “steam” rising from a pot of boiling water. What you see is not water vapor. Water vapor is a clear, colorless gas. The cloud is a mist, made up of tiny droplets of liquid water that condense from water vapor.

Condensation is the change of matter from a gas to a liquid. When a gas changes to a liquid, we say it condenses. If it is a hot sunny day and you have a cold glass of water filled with ice cubes. You notice that drops of water form on the outside of the glass. The drops form as water vapor in the air condenses on the cold glass.

When water vapor loses heat, its particles move more slowly When water vapor loses heat, its particles move more slowly. They move closer together. The water vapor changes to liquid water. When liquid water gets cold enough, it freezes. Freezing is the change of matter from a liquid to a solid. As liquid water loses heat energy, its particles move more slowly. If the water loses enough heat, it becomes a solid—ice. Water freezes at 0˚C

Discussion Question: When the air cools at night, the drops of water called dew form on the grass. How do the drops form? Why do they disappear during the day?

Lesson Review What is the change of gas to a liquid called? Evaporation Condensation Melting Freezing

2. Which statement BEST describes what happens to water when it changes state from a liquid to a solid? Its particles begin to move faster Its particles do not move at all Its particles evaporate Its particles move more slowly.

3. What happens to water when it evaporates? It becomes a solid It becomes droplets It is no longer matter It becomes a gas.

4. What happens to liquid water at 0˚C? It becomes a solid It becomes air It does not change It becomes a gas.