Study Guide
2.1 and 2.2 – States of Matter & Changes of State KEY
1. Solid –
 has a definite shape, definite volume
 keeps its shape in any container, any position
 particles packed closely together
 particles tightly fixed in one position
 they move, only slightly, vibrate in place
2. Crystalline solid –
 particles form in regular, repeating patterns
 patterns create crystals
 salt, sugar, snow are examples
 melts at a distinct temperature
3. Amorphous solid –
 particles not arranged in regular pattern
 doesn’t melt at distinct temp. – becomes soft, might change into another substance
 examples: glass, plastic, rubber
4. Liquid –
 has a definite volume but no shape of its own
 shape changes with container
 particles almost as close as those in solid
 BUT, they move around freely (like marbles in your hand)
 is a “fluid” – substance that flows
5. Surface tension –
 characteristic property of a liquid
 inward force or pull among molecules in a liquid
 brings surface molecules closer together (acts like a “skin”)
 ex: needle and bugs floating on water
6. Viscosity –
 characteristic property of a liquid
 it’s a liquid’s resistance to flowing
 depends on size, shape, and attraction between molecules
 High viscosity (LOTS of resistance) = SLOW FLOW (ex: honey, mayonnaise, molasses)
 Low viscosity (VERY LITTLE resistance) = FAST FLOW (ex: water, vinegar)
7. Gas –
 gas is a fluid, can flow
 has neither shape, nor volume
 particles spread to fill their container
8. Volume –
 the amount of space that matter fills
9. The relationship between gasses and the volume of a container –
 gas particles fill their container, so the volume of a gas is the same as the volume of its container
10. Temperature (and how it relates to the motion of particles of matter)
 the measure of the energy of the motion of matter particles
 more energy means higher temps.
 less energy means lower temps.
11. Melting –
 the change in state from solid to liquid
 ice to water
o Thermal Energy (TE) around ice increases - makes water molecules move faster
o increase TE means increase in temp
o particles break free from their fixed positions – become liquid
 0 degrees Celsius is water’s freezing and melting point
12. Melting point –
 specific temp at which a solid melts
13. Freezing –
 the change in state from liquid to solid
 water to ice
o Thermal Energy (TE) around water decreases - makes water molecules move slower
o decrease in TE means decrease in water’s temp
o particles move so slowly that they take on fixed positions – become solid
14. Vaporizing –
 the change in state from liquid to gas
 water to water vapor
o Thermal Energy (TE) around water increases - makes water molecules move faster
o increase TE means increase in temp
o particles gain enough energy to move independently – become a gas (water vapor)
 100 degrees Celsius is water’s boiling point
15. Evaporation –
 vaporization that takes place only on the surface of a liquid
 ex: a puddle drying up slowly
16. Boiling (and boiling point) –
 vaporization that takes place below and at the surface of a liquid
 ex: pot of boiling water (the bubbles that rise are water that has turned from a liquid state to a
gas state)
 boiling point – temp at which a liquid boils (vaporizes)
17. Condensation –
 the change in state from a gas to a liquid
 water vapor to water
o Thermal Energy (TE) around water vapor decreases - makes water molecules move slower
o decrease TE means decrease in temp
o particles lose enough energy to form a liquid
o ex: fog, clouds, your breath in the winter time
 water vapor – a colorless gas that cannot be seen – clouds, fog, breath are NOT water vapor
18. Sublimation –
 change in state from a solid directly to a gas (no liquid state)
 dry ice (solid carbon dioxide – can’t exist as a liquid at our atmospheric pressure)
o Thermal Energy (TE) around the solid dry ice increases - makes DI molecules move faster
o increase in TE means increase in temp
o particles lose enough energy to break free of their fixed positions and turn directly into a
gas