Phases of Matter

Why do liquids & solids exist? What holds them together? Intermolecular forces -forces of attraction between molecules

Kinetic Energy Atoms & molecules are in constant motion Temperature = measure of average KE of particles in sample of matter

If temperature ↑, the average KE↑ If temperature , then average KE 

Temperature vs. Phase gas & solid at same temp have same average KE but … the particles in the 2 phases move very differently

Gases: Movement: particles are far apart move rapidly from place to place Movement: can move from place to place they can tumble they can shake

Solids: Movement: can only vibrate in back and forth motion particles tightly packed in orderly pattern particles can’t move very much Movement: can only vibrate in back and forth motion

Liquids: Movement: • can vibrate • very hindered movement moving • particles can move a little bit but bump into their neighbors Movement: • can vibrate • very hindered movement moving place to place or tumbling

What is a phase change? It is a transition between phases There are 6 What are they?

Solidification l → s (freezing) 2. melting s → l 3. evaporation l → g 4. condensation g → l 5. sublimation s → g 6. deposition g → s

Melting solid →liquid

source Boiling liquid →gas

Deposition gas→solid

Condensation gas→liquid

Sublimation gas→solid Freezing liquid→solid source

Phase Changes When a substance goes from the gas to a condensed phase (s or l), what happens? particles get closer together and their motion slows down

Phase Changes When a substance goes from solid to liquid or gas, what happens? particles move farther apart and their motion increases