1. UNIT 7: MATTER CH. 2 & 3

2. Matter: Important Characteristics Has mass & volume (takes up space) Made of elements – substance cannot be broken down into simpler substances. 90 naturally occurring elements Smallest unit of an element is the atom.

3. Compound: Important Characteristics Definition: 2 or more different elements chemically combined. Properties of the compound are different than the individual elements in the compound. Elements of a compound are always in the same proportion, no matter how much of the compound exists.

4. Molecule: Important Characteristics Definition: Smallest unit of a substance that keeps all of the physical and chemical properties of the substance. Can consist of atoms of the same element. Ex. O 2, N 2 Acts as a unit.

5. Chemical Formulas: Important Characteristics Represent compounds and molecules Shows how many atoms of each element are in a unit of a substance. Number of atoms of each element is written after the element’s symbol as a subscript. No subscript is used if only 1 atom of the element is present. Examples: H 2 O CO 2 NaClH 2 SO 4

6. Pure Substance: Important Characteristics Matter that has a fixed composition and definite properties. Elements and compounds are pure substances

7. Mixtures: Important Characteristics a combination of 2 or more substances that are not chemically combined. Mixtures often formed by mixing of pure substances. Mixtures can be separated into its components.

8. More about mixtures Heterogeneous Mixture Ingredients are not uniformly mixed For liquids: One cannot dissolve into another – “immiscible” Homogenous Mixture Ingredients uniformly distributed For liquids: One substance dissolves into another – “miscible”

9. Examples of Mixtures Which ones are homogeneous, heterogeneous, miscible, immiscible

10. The air we breathe. A pure substance or a mixture?

11. ASSIGNMENTS FOR TONIGHT  Complete 1-19 in Packet  Read section 2.1 in text.

12. PROPERTIES OF MATTER (2.2 in Text) Physical Properties Properties that are often easy to see or can be measured, Help you determine the uses for different substances: shape color odortexture melting point boiling pointstrengthconductivity magnetism densityphysical state (solid/liquid/gas)

13. Chemical Properties Properties of matter that are generally NOT as easy to observe,. Describe how a substance reacts with substances Related to the elements that make up a substance Some Examples: Reactivity (with oxygen, acid, water) Corrosiveness Flammability (ability to burn) Oxidation (reacts with oxygen)

14. Characteristic Properties Those properties that are most useful in identifying a substance. Ex. Lead- density, malleability, color Helium – very low density, nonreactivity

15. Properties of the element Sodium

16. ASSIGNMENT TO WORK ON #20-26 on p. 5 in packet.

17. ASSIGNMENTS FOR TONIGHT  Complete 1-19 in Packet  Read section 2.1 in text.

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