Describing Matter Physical Science Chapter 1-2 Describing Matter Physical Science

1-2 Describing Matter Objectives 1. Give examples of matter's different properties. 2. Describe how density is used to identify different substances. 3. Compare physical and chemical properties. 4. Explain what happens to matter during physical and chemical changes. New Terms physical property physical change Density chemical change chemical property

Physical Properties Something that can be observed or measured without changing the identity of the matter.

Examples of Physical Properties 1. color 2. odor 3. volume 4. mass 5. thermal conductivity - ability to transform thermal energy from one area to another. 6. State - solid, liquid, gas 7. Malleability - ability to be pounded into thin sheets 8. Ductility - ability to be drawn or pulled into a wire 9. Solubility - ability to dissolve in another substance 10. Density - mass per unit volume

Density is the amount of matter in a given volume. D = m/v and the units are g/cm3, g/mL, kg/m3, or kg/L Density helps us be able to identify substances because the density of a specific substance is always the same at the same pressure and temperature. Also the density of one substance is different from any other substance.

Liquid Layers Liquids will separate by density. The densest will go the bottom and the least dense will be the one at the top. If we shook this up would it blend together? Density does not matter on the amount of the substance.

Chemical Properties Describe a substance based on its ability to change into a new substance with different properties. Example: burning a piece of wood, flammability. Other chemical properties would be: reactivity with oxygen, reactivity with acid, reactivity with water.

Physical Changes A change that affects one or more physical properties. For example - breaking chalk, melting a substance, dissolving a substance, freezing, sanding a piece of wood, bending a paper clip, cutting your hair. Can physical changes be undone? Most of the time they can be undone.

Chemical Changes Chemical Changes - when one or more substances are changed into entirely new substances. The new substances have completely different properties from the original. Examples: baking a cake, soured milk, hot gas formed from a space shuttle blast, the Statue of Liberty being green, using Alka- Seltzer tablets.

Chemical changes often cause color changes, fizzing or foaming, production of heat, sound, light, or odor. Can a chemical change be undone - no because you are making a new substance.