1. Matter  Something that has mass and takes up space  4 different states of matter:  Solid – definite shape and volume  Liquid – definite volume, indefinite shape  Gas – indefinite shape and volume  Gas & vapor are NOT the same thing  Vapor describes the gaseous state of a substance that is usually a liquid or solid at room temp  Plasma – very hot, electrons stripped away  The 5 th state of matter - ????

2. Classifying Matter Matter Pure Substance Element Compound Mixture HeterogeneousHomogeneous

3. Physical Properties  Physical Property – quality or condition of a substance that describes the matter. It can be observed or measured without changing the composition of that substance  odor, color, density, solubility, mp, bp  metals – conductivity, malleability, ductility, luster

4. Physical Properties  Physical properties used to describe matter can be classified as extensive or intensive.  Intensive Properties – depends on the type of matter present, not the amount  density, malleability, conductivity, ductility, luster, mp, bp, color, temp  Extensive Properties – depends on the amount of matter in a sample  mass, length, volume, shape, size  Most properties are INTENSIVE

5. Chemical Properties  Chemical Property – the ability of a substance to undergo a change in composition.  Can only be observed by changing the substance  rust, burn, rot, decompose, ferment, explode, corrode

6. Physical Change – some properties of the substance change, but the composition does not change (still the same substance). boil, freeze, melt, condense, break, split, cut, grind Physical/Chemical Changes Chemical Change – a change in the properties of a substance producing a different composition and a new substance.

7. Practice  Identify the following as element, heterogenous mixture, or homogeneous mixture:  Rubbing alcohol  Ice water  Penny  Paint  Paper  Ink  Brass  Al foil  Salsa Compound Heterog Homogish Homog (unless it is lined) Homog Element Heterog

8. Practice  Decide if the following are a chemical or physical change:  Color fades  Digest lunch  Cutting paper  Plant grows  Cloud formation  Turn on flashlight  Ice melts  Wound heals  Fry an egg Chemical Physical Chemical Physical Chemical Physical Chemical

9. Practice  Classify as intensive or extensive property:  Conductivity  Volume  Density  Color  Temperature  Heat content Intensive Extensive Intensive Extensive

10. Models and Experimental Design  In order to test hypotheses scientists attempt to construct well-designed experimental protocols.  The essential features of a well-designed experiment include:  A single clearly-defined IV  Single clearly-defined response (DV); measured (quantitative better than qualitative)  Other variables as controlled as possible (if not possible then potential effects should be presented)  At least 5 values for IV tested to show trend  Minimum 3 replicants (trials) for each value to assess reliability (precision)  Results designed to be analyzed mathematically or in graphical form

11.  When a complex scientific idea becomes accepted, a model is often used to help make it more comprehensible. The essential features of a good model are that it will :  Correctly describe or illustrate the concept to a level that is acceptable  Help to simplify or enhance visualization to make the concept clearer, or easier to understand.