1. Mixtures, Compounds, and Chemical Changes

2. Compounds Compound: A pure substance consisting of two or more elements combined. Water - H 2 O (liquid) Salt - NaCl (solid) Methane - CH 4 (gas)

3. Chemical Change A chemical reaction is required to separate a compound into separate parts. Chemical Reaction: Any change that involves the formation of a new substance. – Formation of precipitate – Change in color – Formation of gas – Temperature change

4. Chemical Change A chemical change consists of two parts. – Product: A substance formed by a chemical reaction. – Reactants: The starting substances in a chemical reaction. 2 H 2 O 2 H 2 + O 2 Reactants Products

5. Chemical Change Cake Recipe: – Flour, Eggs, Sugar, Chocolate, etc. – Beat together – Bake Once baked, the ingredients are very difficult to separate!

6. Chemical Change What chemical reactions occur in everyday life? Photosynthesis: – 6 CO 2 + 6 H 2 O + light C 6 H 12 O 6 + 6 CO 2 Combustion: – C 3 H 8 + 5 O 2 4 H 2 O + 3 CO 2 + energy Rust: – 4 Fe + 3 O 2 + 6 H 2 O 4 Fe 2 O 3.nH 2 O

7. Mixtures Mixture: Two or more elements that are mixed together but are not chemically combined. Mud - H 2 O + Dirt (Fe, K, Ca) Salt Water - NaCl + H 2 O Salad

8. Mixtures Mixtures combine physically with no specific proportions. They just mix. Solids, liquids, and gasses can be combined to create mixtures. When creating a mixture, no new substances are formed. Each part of the mixture keeps its own properties.

9. Mixtures Homogeneous Mixture: A mixture with the same uniform appearance and composition throughout. – “Homo” prefix meaning same Heterogeneous Mixture: A mixture consisting of visibly different substances or composition. – “Hetero” prefix meaning different Can you come up with some examples?

10. Mixtures Simple mixtures can easily be separated by physical means. Simple Mixtures: – Sand, Dust, Italian Dressing Mixtures can be separated in a variety of ways. – Weight (centrifuge), Evaporation, Sifting, Magnetism.