1. 1.2 Properties and Changes of Matter
Objectives:
Distinguish between physical and chemical properties.
Contrast chemical and physical changes.
Apply the law of conservation of matter to chemical changes.

2. Identifying Matter by Its Properties
Physical properties are those that do not change the composition
They can be quantitative or qualitative.
Qualitative:
The solid is hard.
The liquid boils at a low temperature.
Quantitative:
Ice freezes at 0°C
Iron has a density of 7.86 g/mL

3. States of Matter Three common states of matter:
Solid
Liquid
Gas
Fourth less familiar type:
Plasma: an ionized gas

4. Solid
Solid- a substance in which the particles occupy fixed positions in a well-defined, three-dimensional arrangement.
Definite shape and volume.
Examples:
Iron
Ice

5. Liquid
Liquid - a flowing substance with a definite volume but an indefinite shape.
Definite volume and takes shape of container
Examples:
Water
Mercury
Bromine

6. Gas
Gas – a flowing, compressible substance with no definite shape or volume.
Takes shape and volume of container
Examples
Oxygen
Hydrogen
Helium

7. States of Matter
The state in which matter is found depends on the temperature and pressure.
When you discuss the physical state of matter you are discussing the state at room temperature (20-25°C)
What is the physical state of neon at room temperature?

8. States of Matter – Disc 2

9. States of Matter – Disc 2

10. Physical States
the temperature at which matter changes from one state to another is closely related to its physical state
Water freezes (and melts) at 0°C
Salt melts (and freezes) at 804°C
Oxygen freezes (and melts) at -218°C
The melting points and freezing point are the same for substances

11. Volatile
Volatile – describes a substance that easily change to a gas at room temperature
Alcohol and gasoline are more volatile then water.
Naphthalene (mothballs) is a solid that is volatile.
You can easily smell alcohol, gasoline and mothballs because since they are volatile the molecules are present in the air.

12. Density Density- the amount of matter (mass) in a given unit volume.
The units for density are usually g/mL

13. Density
You fill two beakers; one with cotton balls and one with marbles.
The beaker with the marbles is heavier than the one with the cotton balls, but they both occupy the same volume (the beaker).
The marbles have a larger mass than the cotton balls.
Therefore, the marbles have a larger density than the cotton balls

14. Densities of Some Common Materials
Density, g/mL
Water (4.0°C)
1.000
Ice (0°C)
0.917
Helium (25°C
Air (25°C)
Aluminum
2.70
Lead
11.34
Gold
19.31
Cork
Sugar
1.59
Balsa Wood
0.12

15. Determining Density
One way you can determine density is by using water displacing
Weigh you object. (10 g)
Fill a graduated cylinder with water to a particular mark. Such as, 10mL.
Carefully add you object to the graduated cylinder.
Record the level of the water. ( maybe 15mL)
Next you use the weigh of you object and the level of the water to determine the density.
Your water level started at 10mL and ended at 15mL.
15mL – 10mL = 5mL
Next you take your mass and divide it by your volume.
10g/5mL = 2 g/mL

16. Let’s Try It
Determine the density of the objects provided by your teacher.

17. The Composition of Pennies
Read over this lab on page 38 & 39 of your packet.
Make a flow chart of the procedure for this lab, using only pictures. We may use this technique for more complicated labs in the future.

18. It’s a Liquid, It’s a Solid…It’s Slime
Lab is on page 40 of your packet.
You must wear safety glasses for this lab.
Please, be very careful with the chemicals.
You may work in groups of three.

19. Chemical Properties and Changes
Chemical Properties- can be observed only when there is a change in the composition of the substance.
Describes the ability of a substance to react with another substance or to decompose
Examples:
Rusting
Reactivity

20. Hydrogen Peroxide (H2O2)
Is always stored in brown bottles because it will break down to hydrogen and water gas when exposed to light.

21. Chemical Change
Chemical Change – the change of one or more substance into other substances.
Also called a Chemical Reaction
The sulfuric acid and the sugar
If you add vinegar to baking soda

22. Atoms and Chemical Change
All matter is made up of atoms.
Any chemical change involves the rearrangement of atoms.
When water breaks down it is the rearrangement of the hydrogen and oxygen atoms.
Oxygen molecules
Hydrogen molecules
Water molecules

23. Law of Conservation of Mass
Law of Conservation of Mass – in a chemical change, matter is neither created nor destroyed.
Example: Water molecules
2 H2O  O H2

24. Law of Conservation of Mass

25. Chemical Reactions and Energy
Chemical changes involve some sort of energy change.
Energy – the capacity to do work
Many reactions give off energy and some absorb energy.
Exothermic – gives off heat
Endothermic - absorbs heat

26. Chemistry and Chemical Reactions
Are all around you and are in everything that you do.

27. Properties

28. Review Distinguish between a liquid, solid, and a gas.
Give an example of a physical change and a chemical change.
What are two substances that would be considered volatile?