Heat, Particle Theory, and

States of Matter

Or: Hot makes BIG, Cold makes SMALL.

Review Question

What are the changes from each state of matter called? Fill in the blanks in the chart you’re given and hand in when done.

Review: Matter

Review: Matter

•  3 states of matter: solid, liquid and gas

•  solids are made up of a latticework

of tiny molecules that are being attracted to and repelled from one another

Particle Theory 1.  all matter is made up of

extremely tiny particles

2.  each pure substance has its own kind of particle

3.   the particles are in constant motion

4.   particles are attracted to one another

5.  there are spaces between particles

6.   temperature affects the speed at which particles move

slow getting faster…

HEAT

crazy fast!

less

mor

e 5.  Temperature affects the speed of particles

Attraction

wea

ker

stro

ng

er

close together strong force

farther apart weaker force

very far apart very weak force

4.  particles are attracted to one another

Question Time!

How would particle theory explain the fact that a chocolate Easter Bunny melts when left out in the sun?

Solids, Liquids, and Heat

Solids, Liquids and Heat •  heat makes the molecules

(particles) in the solid start moving faster

•  once the particles are moving fast enough, the forces of attraction between particles are not strong enough to hold them together anymore and the latticework breaks apart

•  instead of vibrating against one another, the particles slip and slide over one another and melt

•  When the heat is taken away, the chocolate freezes into a solid because the molecules are moving slower and the forces of attraction are strong enough to keep them together

What do Vapour and Density have to do with Evaporation and Condensation?

Liquids, Gases and Heat •  Particles in a liquid are moving

quickly past one another •  as a liquid is heated, some of

the particles near the top “pop off”, turning into a vapour or gas

•  Vapour = evaporation •  When a gas is cooled, the

particles move and can’t resist their forces of attraction

•  There are more particles in a smaller space in a liquid than in a gas

•  water is more dense than water vapour •  dense = condensation

Lab: Melting Away