1. Pure Substances Mixtures Physical and Chemical Changes

2. Everything that has mass and volume is called matter.

4. Matter that has a fixed composition and definite properties. (chemical and physical)

5. There are two kinds of pure substances Elements Compounds

6. Elements Substance that cannot be separated or broken down into simpler substances by chemical means. Ex’s- any box on the periodic table Made of only 1 type of atom –The smallest unit of an element that maintains the properties of that element HUH?

7. The smallest unit of an element that maintains the properties of that element??? The element sodium has certain properties –11 protons, 11 electrons…boiling point, etc

8. Compounds Substance made of atoms of 2 or more different elements that are CHEMICALLY combined. Always have a chemical formula to represent it Elements are combined in a definite way and this changes their properties Na - lethal if ingested Cl- lethal if ingested NaCl- table salt

9. Compounds Can be decomposed into simpler substances by chemical changes, always in a definite ratio Elements Cannot be decomposed into simpler substances by chemical changes Na (sodium) NaCl (sodium chloride/salt)

10. Fixed composition Cannot be separated into simpler substances by physical methods (physical changes) Can only be changed in identity and properties by chemical methods Properties do not vary Can be expressed with a chemical formula –Ex H2O, NaCl, H

12. Mixtures are two or more substances that are physically combined. (NOT chemically combined like a pure substance) May be separated into pure substances by physical methods

13. Examples of Mixtures

14. Components retain their characteristic properties and can be separated by physical means. http://videos.howstuffworks.com/hsw/22540-together-but-separate- suspensions-video.htmhttp://videos.howstuffworks.com/hsw/22540-together-but-separate- suspensions-video.htm This sand and iron filings mixture can be separated using a magnet.

15. Two types of mixtures

16. Homogenous mixtures look the same throughout Types: solutions, alloys, etc. Example: salt water, brass

17. Have the same composition throughout Components are indistinguishable May or may not scatter light Particle size is small

18. Can they still be separated by physical means ? YES!!! It may be more complicated, but it can be done…distillation, centrifugation

19. Solutions are … homogenous mixtures that do not scatter light. separated by distillation or evaporation. created when something is completely dissolved in pure water. Examples: sugar water, salt water

20. Parts of a Solution Solute- substance that dissolves in solvent ex. Salt (“U dissolve”) Solvent- substance that does the dissolving (ex.water) Well, not really, because you don’t dissolve, but you get the picture

21. Why don’t you dissolve? You are not “Miscible” –Miscible- two or more liquids that can dissolve into each other –Immiscible- liquids that do NOT mix Ex- oil and water

22. Heterogeneous mixtures are composed of large pieces that are easily separated by physical means (ie. density, polarity, metallic properties).

23. Do not have same composition throughout Components are distinguishable Particle size is medium or large Examples: fruit salad, vegetable soup, etc.

24. Tyndall Effect Light scattering caused by particles

25. Types of heterogeneous mixtures include: Colloid –medium particles Suspension-large particles

26. Colloids are heterogeneous mixtures. They can be described as a substance trapped inside another substance. They can be identified by their characteristic scattering of light. For example: air trapped inside the fat molecules in whipped cream, mayonnaise,

27. A property of suspensions is that the particles will settle out when the mixture is allowed to stand Ex. Orange juice with pulp, muddy water