There are currently 118 known elements that make up all matter. Elements are pure substances that contain only one type of atom, while compounds are made of two or more elements or other compounds. Mixtures have a variable composition because their ingredients are not uniformly distributed.

1. 2.1-2.2 Powerpoint
By Nathan Rosenberg

2. Elements
• There currently are 118 elements
• A element is a substance that cannot be broken down into simpler
substances
• A element has a fixed composition because it contains only one type of
atom

3. Pure Substances
• A pure substance is matter that always has the same composition.

4. Compounds
• A compound is a substance that is made from two or more simpler
substances
• The simpler substances are either elements or other compounds
• Oxygen is a compound
• Silicon is a compound

5. Mixtures
• The properties of a mixture can vary because the composition is not fixed.
• When ingredients are not evenly distributed.

6. Physical Properties
• Viscosity is the resistance to flowing .
• Conductivity is a materials ability to allow heat to flow through it.
• Malleability is the ability of a solid to be hammered without shattering
• Hardness can be compared by scratching two materials and seeing which
scratches which.
• Melting and boiling point
• Density can be used to test purity of a subject

7. Evaporation
• A process used to isolate a solid dissolved in a liquid
• Warning: You are not going to isolate all of the substances

8. Filtration
• A process that separates materials based on their sizes

9. Distillation
• A process that separates the substances in solution based on Boiling point

10. Flammability and
Reactivity
• Flammability is a material’s ability to burn is the presence of oxygen.
• The property that describes how readily a substance combines chemically
with other substances is reactivity.
• Flammability and reactivity are both qualitative results.

11. Recognizing Chemical
Change
• A change in color
• Production of gas
• Formation of a precipitate

12. Is a change chemical or
Physical
• When matter undergoes a chemical change, the composition of the matter
changes . When matter undergoes a physical change, the composition of the
matter remains the same.

13. 1. What is a mixture?

14. 2. What is the down
side to evaporation?

15. 3. How do you
recognize chemical
change?

16. 4. How do you perform
a distillation?

17. 5.How do you know if
a change is chemical or
physical?