1. Phases of Matter, and Melting/Freezing Point
Solid
Liquid
Gas

2. Today’s Objective
SWBAT: Analyze the 3 states of matter and melting/freezing point.

3. Defining States of Matter
States of matter are NOT defined by what they are made of.
Example: solids can be elements (gold), compounds (Salt = NaCl), or mixtures (butter)
Element (Au)
Compound (NaCl)
Mixture (Milk, Salt, etc)

4. Defining States of Matter
States of matter are defined by whether they hold SHAPE and VOLUME
Element (Au)
Compound (NaCl)
Mixture (Milk, Salt, etc)
ALL KEEP THE SAME SHAPE AND VOLUME = Solids

5. Defining States of Matter
Solids – have a definite SHAPE and VOLUME.
Element (Au)
Compound (NaCl)
Mixture (Milk, Salt, etc)
ALL KEEP THE SAME SHAPE AND VOLUME

6. Particle View of a Solid
Particles in a solid are PACKED CLOSELY together and they are in a FIXED POSITION.
Particles vibrate in place
This fixed, closely packed arrangement causes a solid to have a definite shape and volume

7. Liquids
Liquids – has definite VOLUME but no defined SHAPE
100 ml

8. Particle View of a Liquid
Packed CLOSELY (like a solid), but move FREELY around each other (must stay in contact).
Because liquid particles are free to move, a liquid has no definite shape. However, it does have a definite volume.

9. Gases Gases - do NOT have definite SHAPE or VOLUME.
Bromine gas fills up the entire volume of the container

10. Particle view of a Gas
Particles can MOVE FREELY and will either fill up or squeeze into available space.

11. Changes in States of Matter
Thermal Energy – heat energy.
More thermal energy = More particle movement

12. Changing States Solid Gas Liquid Increase Thermal Energy (Heat up)
Decrease Thermal Energy (Cool off)

13. Melting Point
The melting point is the temperature at which a substance changes from a solid to a liquid.

14. Melting point
Melting Point - Specific temperature when solids turns to liquid.
Each pure substance has a SPECIFIC melting point.
Examples:
M.P. of Water = 0°C (32°F)
M.P. of Nitrogen = °C ( °F)
M.P. of Silver = °C ( °F)
M.P. of Carbon = °C ( °F)

15. Melting Point Solid Liquid
Particles of a solid vibrate so fast that they break free from their fixed positions.
Occurs until of ALL the solid turns to liquid.
Increasing Thermal Energy
Solid
Liquid
Melting point

16. Freezing Point
Freezing Point – Temperature at which a liquid turns to solid.

17. Freezing Point
Freezing Point – Specific temperature at which liquid turns to solid.
Generally freezing point = melting point

18. Freezing Point Particles lose energy and begin to vibrate very slowly.
Occurs until ALL liquid turns to solid.

19. Boiling Point and Characteristic Properties

20. Boiling Point
The temperature at which a liquid becomes a gas is called the boiling point.

21. Boiling Gas Liquid Boiling – change from liquid to gas
Vaporization happens when particles in a liquid gain enough energy to form a gas.
Increasing Thermal Energy
Gas
Liquid
Boiling point

22. Two Kinds of Vaporization
Evaporation – vaporization that takes place only on the surface of the liquid
Boiling – when a liquid changes to a gas BELOW its surface as well as above.

23. Boiling Point Boiling Point – temperature at which a liquid boils
Each pure substance has a SPECIFIC boiling point.
Examples:
B.P. of Water = 100°C (212°F)
B.P. of Nitrogen = °C ( °F)
B.P. of Silver = 2162 °C (3924 °F)
B.P. of Carbon = 4027 °C (7281 °F)

24. Notice temperature is constant while ice melts!

25. Boiling Point and Melting Point

26. Sublimation
Sometimes a solid can change directly to a gas when heat energy is added.
This process is called sublimation.

27. Characteristic Properties
Characteristic Property – Any property that helps to identify what a substance is.
Property is the same whether you have a small sample or a large sample.
Examples
Density
Freezing Point
Melting Point
Boiling Point