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Everything around us is made of stuff called matter, and all matter is made of atoms. Matter is anything that comes in three varieties, what scientists call phases. There are solids like rocks, cookies, and desks. There are liquids like water, honey, and juice. And there are gases, we breathe air and the helium in balloons. The main difference between the three phases is how fast the matter’s atoms move.

All atoms move around because they have energy. The more energy that’s in something, the faster the atoms move. Atoms in an ice cube don’t move very much – they’re frozen in place. The atoms in liquid water slip and slide around – that’s why you can pour it and spill it. Water vapor atoms are moving pretty fast – that’s why they float around in air (a mixture of other gasses). Changing an object’s phase of matter is just a matter (ha, ha) of adding energy to atoms or taking it away.

Heating adds energy to atoms, and cooling takes energy away from atoms. If you fried an ice cube in a pan on a stove, you would see all three phases of matter – ice cube, liquid water, and water vapor.

Watch the “Phases of Matter” show and your science will be solid!

The Big Ideas

  • Everything is made of matter, and matter is made of atoms.
  • Matter exists in three phases, solids, liquids, and gases.
  • Adding or taking away energy makes matter change phase.

Did You Know That?

  • Dry ice is a solid that goes directly into a gas without becoming a liquid along the way? Scientists call this process “sublimation.”
  • Absolute Zero, -273.15 degrees Celsius (-459.7 degrees Fahrenheit), is the temperature at which no molecules would be moving at all?
  • Gases always conform to the shape of their container? Squeeze a balloon.

Books of Science!

  • “Solids, Liquids and Gases” by Melvin Berger. Published by G.P. Putman’s Sons, 1989.
  • “From Glasses to Gases: The Science of Matter” by Dr. David Darling. Published by Dillon Press, 1992.
Bill Nye