Matter and Energy If you forget to set the timer when you are making cookies, how do you know when they are ready? How does that happen?

All matter is made of particles (atoms/molecules/formula units) Particles are always moving Higher temp. – faster the particles move. Same temp - heavier particles move slower than lighter ones. When particles collide – one gains energy and the other loses energy

Solid – particles in a fixed position Liquid – particles closely packed, but can still slide around Gas – particles in constant motion, rarely stick together States are physically different

Solids have a rigid shape Tightly packed particles = strong attraction Little movement – vibrations in bonds Little movement = small amount energy Definite shape & definite volume (doesn’t change)

Liquids take the shape of their containers Indefinite shape & definite volume Less attraction between particles Different shaped glasses – but same volume More movement than solids = more energy than solids

Gases are free to spread in all directions Do balloons have different shapes? (Don’t forget about balloon animals) If the you leave the top off a perfume bottle, why can you smell it from a distance?

Properties of Gases Indefinite shape & indefinite volume Little to no attraction in particles A lot of space = a lot of motion= a lot of energy Dangerous to heat – can cause explosions

Energy IS NOT MATTER! Ex: light, heat, and sound Heat (energy) is added – particles move faster. Heat (energy) is released – particles move slower http://mutuslab.cs.uwindsor.ca/schurko/animations/waterphases/status_water.htm

Phase changes Process of changing from one phase to another Solid Liquid Gas

Energy must be added to cause melting or evaporation

Phase Diagram of H2O A critical point is where the properties of two phases become indistinguishable from each other

Gases exert pressure A balloon will pop if its internal pressure increases too much. Internal pressure = force of particles n the balloon walls Blow up and balloon and le tit go, gases under pressure will escape container if possible. Ex: hairspray, air freshener, spray paint