1. What’s the MATTER, part II

2. Types of Matter  Pure Substance- Matter with a fixed composition It has distinct properties Examples =elements compounds

3. Pure substance = Only ONE element or compound (distilled water). Pure substance = Only ONE element or compound (distilled water). Some Examples:

4.  Mixtures- Most matter is a mixture The composition is not fixed (changes from sample to sample) Two Types – Homogeneous Heterogeneous

5. Some Examples:  Mixtures are variable combinations of 2 or more pure substances. Heterogeneous – visibly separate phases Homogeneous – Same throughout

6. Air is a mixture of several gases. Name Formula amount Nitrogen N 2 78 % Oxygen O 2 21 % Argon Ar 1 % Carbon CO 2 0.03 % Dioxide

7. Homogeneous Mixtures  Composition is uniform throughout Solution-  Particle size = 0.01 – 1 nm  Doesn’t settle out upon standing  Can’t be separated by filtering  Doesn’t scatter light  Example = distilled water

8. Colloid-  Particle size = 1 – 1000 nm  Doesn’t settle out upon standing  Can’t be separated by filtering  Scatters light (Tyndall Effect)  Examples = milk, gelatin, smoke

9. Heterogeneous Mixtures  The sample varies in composition, properties and appearance  No uniformity  Particle size is greater than 1000 nm  Particles settle out upon standing  Can be separated by filtration  Might scatter light  Examples = soil, trail mix, pond water

10. Physical vs. Chemical Properties  Every substance has a unique set of properties (characteristics that identify that substance)  Physical Properties- Properties that can be measured without changing the identity and composition of the substance

11.  Physical Property Examples- Color Odor Density Melting Point Boiling Point Hardness Solubility

12. Physical Change  A change in matter from one form to another without changing its chemical properties (most can be reversed)  Examples = Change in state Dissolving Compressing

13. Chemical Properties  Properties that describe the way a substance may change to form other substances  Only observed when a chemical reaction takes place

14. Chemical Property Examples  Heating to combustion  Reactivity with water or acid  Flammability  Corrosion  Decomposition

15. Law of Conservation of Mass  In a physical change or a chemical reaction, mass is neither created or destroyed (Antoine Lavoisier)

16. Is the composition uniform? NoYes MATTER Can it be physically separated? Homo- geneous Mixture (solution) Hetero- geneous Mixture Compound MIXTURE PURE SUBSTANCE Yes No Can it be chemically decomposed? No Yes Suspensions Element Colloids

17. Putting sand and salt together makes a compound. an element. a mixture. a solution.

18. Pure Water is a compound. an element. a solution. a mixture. Pure Water is a compound. an element. a solution. a mixture.

19. Tap Water is a compound. an element. a solution. a mixture. Tap Water is a compound. an element. a solution. a mixture.

20. Salt (NaCl) is a common substance. Salt is which of these? atom element compound mixture Salt (NaCl) is a common substance. Salt is which of these? atom element compound mixture

21. Which formulas represent compounds? O 2, H 2 O 2 CO 2, H 2 O H 2, CO 2 H 2, O 2 Which formulas represent compounds? O 2, H 2 O 2 CO 2, H 2 O H 2, CO 2 H 2, O 2

22. Which of the following is a compound? oxygen water nitrogen air