Phases of Matter

1. Phases of Matter

2. 4 of them…What are they • Solids- • Have a definite shape and definite volume. Atoms are very tightly packed together • Liquid- • Atoms are not packed as tightly. Free to move. They take the shape of its container. • Have a definite volume but no definite shape • Gas- • Does not have a definite shape or volume. Tend to spread far away from another, but can also be packed very tightly together. • Plasma • Very rare on earth. Has extremely high energy and dangerous to living things. Examples are the suns and stars.

4. Phase Changes • Solids have less energy than liquids. • Liquids have less energy than gas • In order to change phases, energy either has to be added or removed.

5. There are 5 phase changes • Melting • Freezing • Vaporization • Condensation • sublimation

6. Melting • The change of a solid to a liquid. • Occurs when a substance absorbs energy. • Point at which solid changes to a liquid is called it’s “melting point” • Why do we pour salt on icy side walks? • Lowers the freezing point. The water won’t freeze Until the temp reaches -20 degrees. • The opposite occurs when liquid changes to a solid. • Freezing. Substance loses energy. • Why do we use anti-freeze in cars? • Again, it lowers the freezing point so that the car’s engine doesn’t freeze up. Ice vs salt

7. Vaporization • The change of a substance from a liquid to a gas. • Liquid needs to absorb energy in order to change into gas. • Boiling water. What happens if you boil a pot of water overnight? • All the liquid water changes to gas

8. Condensation • If a substance in the gas phase loses energy, it changes into a liquid. • Some examples: • Ice cold drinks • Bus windows • Walls of a tent at night • Dehumidifier

9. Sublimation • When an object goes from a solid to a gas. • It skips the liquid phase. • Dry Ice-what is it? • Solid carbon dioxide (CO2) • We normally only see carbon dioxide as an invisible gas. But if cold enough we can freeze it. Dry ice