1. Grade 7 Science Unit 3: Mixtures & Solutions: The Particle Theory

2. Particle Theory of Matter n All matter is made up of tiny particles. n These particles are always moving… they have energy.

3. n There are spaces among particles. n There are attractive forces between the particles. n The particles of one substance differ from the particles of other substances.

4. Matter can be either: n Pure substance n Mixture

5. Pure Substances... n ALWAYS appear as uniform throughout n A material that is only composed of one type of particle.

6. Sea shell- calcium carbonate

7. Examples of Pure Substances sugar gold, copper distilled water (H 2 O) carbon dioxide (CO 2 ) Table salt

8. Mixtures... n Composed of two or more types of particles. n MAY have distinct visible components.(heterogenous) n MAY appear uniform throughout. (homogeneous)

9. n They are the physical combination of two or more pure substances. + Sugar Water =

10. Examples of Mixtures… salt water, kool-aid chocolate chip cookie muddy water salad dressing air

11. Heterogeneous Mixtures pg 234 Also known as mechanical mixtures. n Contains 2 or more different particles and it is very easy to see the different parts. n It is easy to separate by hand or mechanical means such as filtration.

12. Examples n Chocolate chip cookie n Pizza n Cement n Salad dressing

13. Homogeneous Mixtures pg 234 n Also known as a ‘solution’ n Contains 2 or more different particles but the parts seem to be the same throughout. You cannot see the different parts.

14. Examples: n 14 Karat gold(58% gold & 42% other metals) n Stainless steel pan (iron and chromium) n Sugar and water n Salt water n Vegetable oil.

15. Heterogeneous, Homogeneous or Pure Substance: Cooking oil

16. Heterogeneous, Homogeneous or Pure Substance: n Beach Sand

17. Heterogeneous, Homogeneous or Pure Substance: n Oxygen

18. Heterogeneous, Homogeneous or Pure Substance: Fountain drink

19. Heterogeneous, Homogeneous or Pure Substance: n Salad

20. n Copper Heterogeneous, Homogeneous or Pure Substance:

21. Student Activity n Complete a three tab foldable which includes pure substances, heterogeneous mixture and homogeneous mixture. n Complete the worksheet

22. Is it a solution, mechanical mixture or pure substance? 1) You can use a microscope

24. Is it a solution, mechanical mixture or pure substance 2. If a liquid is a mixture, pour it through filter paper. See what happens…

25. Is it a solution, mechanical mixture or pure substance 3. The Tyndall Effect

26. If it is a solution (Homogeneous mixture) you will not see a beam of light. Heterogeneous you will…