1. The Classification of Matter …it matters (Ch. 2)

2. 2.1 Matter Matter has mass and volume. –The smallest particles in matter are called atoms. –All matter is made of atoms. A molecule is made up of two or more atoms stuck together. Ex: H 2, H 2 O. A molecule can be a compound or an element. A particle is one small unit of matter. Example: A molecule or an atom

3. Matter An element is ONE type of atom. Ex: gold contains only gold atoms. Ex: H 2, Au A compound is a substance that contains two or more types of atoms. –Ex. CO 2 –A compound always has the same number of atoms in each molecule.

4. States of Matter SolidLiquidGas Definite shapeIndefinite shape Definite volume Indefinite volume

5. 2.2 Properties of Matter Physical properties include odor, color, volume, state (gas, liquid, solid), density, melting point, and boiling point. Chemical properties refer to the ability of a substance to form a new substance. Ex: Iron reacts with water and makes rust (iron oxide).

6. 2.2 When you melt ice or boil water, the state of water changes. But the molecules of H2O are still there. A physical change does not change the composition of the substance: phase changes (melting, freezing, boiling, condensing, sublimation), breaking, bending.

7. In a chemical change, a substance changes into one or more new substances. Example: Burn, rust, rot –Transfer of energy (heat, light) Burning wood –A change in color Eggs cooking –A gas being produced Burning wood –The appearance of a solid.

8. Chemical Change When electricity passes through water, the water changes into hydrogen gas and oxygen gas. Are the molecules of H2O still there after the change? No, they’re not.

9. Quiz: Physical or chemical change? Chemical. Baking soda combines with vinegar to make carbon dioxide, acetate and water.

10. 2.3 Classifying matter A mixture has more than one substance. –Ex.: Air contains many gasses: nitrogen, oxygen, water, argon, carbon dioxide… How is air in the city different from air in the country? Can you think of other examples?

11. 2.3 Classifying matter Mixtures of metals are called alloys. –Ex. Brass is a mixture of copper and zinc. Pure substances contain only one substance. They can be elements or compounds. Ex: H 2 O, H 2

12. Heterogeneous mixtures have different parts, and each part has different propertiesEx: Sand and water. A mixture can be separated into pure substances. A heterogeneous mixture can be separated by filtration.

13. 2.3 Classifying matter Homogeneous mixtures or “solutions” have the same composition throughout. –All parts look the same. –Particles are too small to see.

14. Heterogeneous or Homogeneous (solution) Hint: What are the beams of light hitting?

15. For example, seawater is a mixture of salt and water. The salt can be separated from water by distillation. Distillation is the separation of a mixture by boiling the liquid and condensing the gas. When sea water is boiled, the salt stays in the container, while the steam escapes.