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. 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

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. 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 Review1.What is the change of gas to a

liquid called?

a.Evaporationb.Condensationc.Meltingd.Freezing

2. Which statement BEST describes what happens to water when it changes state from a liquid to a solid?

a.Its particles begin to move fasterb.Its particles do not move at allc.Its particles evaporated.Its particles move more slowly.

3. What happens to water when it evaporates?

a.It becomes a solidb.It becomes dropletsc.It is no longer matterd.It becomes a gas.

4. What happens to liquid water at 0˚C?

a.It becomes a solidb.It becomes airc.It does not change

d.It becomes a gas.