This document describes the three states of matter - solids, liquids, and gases - and the changes between each state. It defines key terms like melting, freezing, boiling, evaporation, condensation, and sublimation. Solids have a definite shape and volume, with particles tightly packed in a fixed position. Liquids have a definite volume but no shape, as particles move freely yet remain touching. Gases have no definite shape or volume, as particles are far apart and expand to fill their container. Changes between states involve the absorption or release of thermal energy.

1. Solids, Liquids, and Gases
Ch. 2

2. Lesson 1
States of Matter

3. How many states of matter can
you spot in the picture?
Solid
Liquid
Gas

4. Solids, Liquids, and Gases: Which is which?

5. Describing Solids
•Solid: Has a definite shape
and a definite volume
•What does volume mean
again? (The amount of space
an object fills)
•Particles are tightly packed
•Particles may vibrate in place
but will not move around

6. Solid Showdown
VS.

7. Types of Solids
Amorphous Solids
• Particles are not arranged in a
particular order
• Do not melt at a particular
temperature
Crystalline Solids
• Particles are all uniformly
organized
• Melt at a certain temperature

9. Describing Liquids
• Liquid: Has no definite shape
but does have a definite
volume
• Particles all touch but are not
as tightly packed as solids
• Freely moving particles

10. Characteristics of Liquids
• Surface tension: An inward force that
pulls particles closer together
• Due to high attraction between water
molecules
• Allows some insects to walk on the
surface of water
• Viscosity: Resistance to flowing
• Depends on the size and and shape of
particles
• Highly viscous = flow slower
• Low viscosity = flow quickly

11. Describing Gases
• Gas: Has no definite shape
or volume
• Particles do not touch each
other
• Particles expand to fill a
container

12. Lesson 2
Changes of State

13. Energy
• The two main types of energy:
1. Potential: Stored energy
2. Kinetic: Energy in motion

14. Temperature
Temperature: How hot or cold something is (measure of kinetic energy)

15. Thermal Energy
• Thermal Energy: The total energy of the motion of all the particles in
an object (kinetic and potential energy)
• When matter changes, thermal energy is usually released or
absorbed.

16. Changes of State Between Solid and Liquid
• Melting: When solid changes to liquid
• Melting Point: The temperature at which a substance’s particles vibrate so much
that they break free from their fixed position.
• Water’s melting point is 0℃

17. Changes of State Between Solid and Liquid
• Freezing Point: The temperature at which a liquid changes to a solid
• Water’s freezing point is 0℃

18. Changes of State Between Liquid and Gas
Evaporation
• Vaporization that takes place
only at the surface of a liquid
• Evaporation can occur at varying
temperatures
Boiling
• Vaporization that takes place
both below and at the surface of
a liquid
• Boiling Point: The temperature
at which a liquid begins to boil
• Boiling point of water is 100℃
Vaporization: The change in state from a liquid to a gas…two types: evaporation & boiling

19. The Effect of Pressure
Pressure = Force / Area

20. Atmospheric Pressure
•Atmospheric Pressure: The air that surrounds us that is always
applying pressure
•As altitude increases, atmospheric pressure and air density
decrease
•Less dense air will have less atmospheric pressure (like on top
of a mountain!)….this means water will boil quicker
•Boiling point is reached easier when less pressure is being
applied

22. Condensation
• Condensation: The change in state from a gas to a liquid
• In other words, it is the opposite of vaporization
• This is how clouds are formed! Tiny water droplets become suspended in the air

23. Changing State from Solid to Gas
• Sublimation: Occurs when the surface particles of a solid fain enough energy that
they form a gas
• Particles do not first become a liquid…they just go from solid to gas
• Example: Dry ice changes directly from a solid to a gas