Solids, Liquids, and Gases: What's Matter Made Of?

What You'll Learn

• Solids keep their own shape (ice, rock, a brick)
• Liquids flow and take the shape of their container (water, juice)
• Gases spread out to fill any container (air, steam)
• Water can be all three states: ice (solid), water (liquid), steam (gas)
• Adding heat changes solid to liquid to gas; removing heat reverses it

Words to Know

Matter

Anything that takes up space and has mass

"The chair and the air are both matter."

Solid

Matter that keeps its own shape

"A rock is a solid."

Liquid

Matter that flows and takes the shape of its container

"Juice is a liquid."

Gas

Matter that spreads out to fill any space

"The air we breathe is a gas."

Heat

Energy that can change matter from one state to another

"Heat melted the ice into water."

States of matter

The three forms matter can take: solid, liquid, and gas

"Ice, water, and steam are three states."

Check What You Learned

Fun Facts

• Matter is anything that takes up space and has mass

  Source: NASA, "What Is Matter?"

• Solids have a fixed shape and volume because their particles are packed tightly together

  Source: American Chemical Society, "States of Matter"

• Liquids have a fixed volume but take the shape of their container because their particles can slide past each other

  Source: American Chemical Society, "States of Matter"

• Gases have no fixed shape or volume and spread out to fill any container because their particles move freely

  Source: American Chemical Society, "States of Matter"

• Water can exist in all three states: ice (solid), liquid water, and steam/water vapor (gas)

  Source: USGS Water Science School, "Water Properties"

• Adding heat to a solid causes it to melt into a liquid; adding more heat turns the liquid into a gas; removing heat reverses the process

  Source: NASA, "States of Matter"