1. Ch. 18: classification of Matter
Secton 1: Composition of matter

2. Recall:
What is matter?

3. Substance A type of matter with a fixed composition Examples:
An element (Like Oxygen or Carbon)
A compound (Like Water or Salt)

4. Elements A substance with atoms that are all alike Examples:
Everything in the periodic table of elements

5. Notable Elements and their uses
Tungsten= forms the filament in light bulbs; highest melting point of any metal
Gold= resists corrosion; coats space vehicles
Americium= in smoke detectors; but radioactive
Lead= high density; excellent barrier to radiation; x ray protection
Titanium= strong and lightweight; excellent for body implants
Aluminum; excellent reflector of heat; used in cooking

6. Compounds
Pure substance in which the atoms of two or more elements are combined in fixed proportions
Examples: Salt, water, chalk

7. Mixtures
2 types:
Heterogeneous Mixture= a mixture in which different materials can be distinguished easily (i.e. salad).

8. Homogeneous Mixtures
Contains two or more gaseous, liquid or solid substances blended evenly throughout (i.e. vinegar, soda in a sealed bottle).
Another name for homogeneous mixtures are solutions= mixture of particles so small they cannot be seen with a microscope and never settle to the bottom of the container.

9. Examples

10. COLLOIDS
Mixture with particles that are larger than those in solutions but not heavy enough to settle out
Examples: Fog and milk

11. Difference between colloid and a solution?
Test using the Tyndall effect
Scattering of light beam as it passes through a colloid

12. Suspensions
Heterogeneous mixture containing a liquid in which visible particles settle