1. Matter has mass and takes up space

2. Pure substance Can not be broken down or separated by physical processes Can not be broken down or separated by physical processes Uniform and definite composition…any sample of it is like any other sample of it Uniform and definite composition…any sample of it is like any other sample of it

3. Elements Can not be separated into simpler substances by chemical change Can not be separated into simpler substances by chemical change Atoms or elements: Atoms or elements: –Organized on the Periodic Table –Names or symbols are used Aluminum, iron, hydrogen, oxygen Aluminum, iron, hydrogen, oxygen Al, Fe, H, O Al, Fe, H, O

4. Compounds: Made from two or more atoms or two or more elements combined by a chemical reaction to from a new compound Made from two or more atoms or two or more elements combined by a chemical reaction to from a new compound Contain two more elements in a fixed proportion or ratio Contain two more elements in a fixed proportion or ratio Example: H 2 O 2 hydrogen atoms 1 oxygen atom…two types of atoms combine in strict ratio to form new compound Example: H 2 O 2 hydrogen atoms 1 oxygen atom…two types of atoms combine in strict ratio to form new compound Magnesium oxide always 60% Mg, 40% O Magnesium oxide always 60% Mg, 40% O

5. Molecules are the smallest units of compounds that retain the properties.

6. More elements and compounds Elements Elements –Copper…Cu…metal –Sulfur…S…yellow powder –Oxygen…O…colorless gas Compound Compound –Copper Sulfate…CuSO 4 –1 Cu, 1 S, 4 O –combine chemically in definite proportions to form different pure substance

7. !!REMEMBER!! ELEMENTSandCOMPOUNDSareBOTH PURE SUBSTANCES

8. How did scientists know? Used techniques to figure out which substances were the simplest Used techniques to figure out which substances were the simplest –Rust comes from iron and oxygen…mass increases –Water comes from hydrogen and oxygen…electricity breaks it up

9. Mixture A physical blend of two or more pure substances A physical blend of two or more pure substances Mixtures do not always contain the same proportions or amounts of the substances…they have variable composition Mixtures do not always contain the same proportions or amounts of the substances…they have variable composition –Lemonade can be a little sweet or very sweet depending on how much sugar is mixed in

10. Two types of mixtures Homogeneous… Homogeneous… –Prefix “homo-” means the same Heterogeneous Heterogeneous –Prefix “hetero-” means different

11. Homogeneous Solution is another name for a homogeneous mixture Solution is another name for a homogeneous mixture A mixture in which two or more substances are uniformly spread out…parts aren’t visibly different… uniform composition A mixture in which two or more substances are uniformly spread out…parts aren’t visibly different… uniform composition –EXAMPLES Air, salt water, stainless steel, pop Air, salt water, stainless steel, pop

12. Heterogeneous A mixture in which different materials are easily distinguished…not uniform composition A mixture in which different materials are easily distinguished…not uniform composition –EXAMPLES: chocolate chip cookies, granite, salad dressing, pop if you can see the bubbles chocolate chip cookies, granite, salad dressing, pop if you can see the bubbles

13. Some heterogeneous mixtures might fool you! Colloid Colloid –heterogeneous mixture in which the particles never settle…scatters light EXAMPLE: milk, gelatin EXAMPLE: milk, gelatin Suspension Suspension –heterogeneous mixture containing liquid in which the particles settle…scatters light EXAMPLE: pond water EXAMPLE: pond water

14. Remember… Solutions are homogeneous mixtures. Solutions are homogeneous mixtures. –Substances are mixed uniformly with no visible difference –Solutions do not scatter light…you can not see the particles

15. Let’s sort it all out…!