Chapter 2: Matter and Change

1. Chapter 2: Matter and Change

2. Notes overview • Learn how to classify matter: • By composition • By state • Identify properties of matter • Learn how to separate substances • Differentiate between changing substances chemically and physically

3. Properties of matter • Extensive Properties • depends on the amount of matter present in a sample • Examples: mass, volume • Intensive Properties • depends on the type of matter (not amount) • Examples: hardness, density

4. The physical side of matter • Physical Property • quality or condition of a substance that can be observed without changing the substance’s identity (composition) • Examples: hardness, color, conductivity, malleability, ductility, melting point, boiling point, state • Physical Change • changing the form of a substance without changing the identity (composition) • properties remain the same

5. The chemical side of matter • Chemical Property • ability of a substance to undergo changes in identity (composition) through chemical reaction • Chemical Change • change that produces matter with a different identity (composition) than the original matter • Products have different properties • Examples: burning, rusting, fermenting, decomposing

6. Classifying matter by composition • The focus is on the type and amounts of atoms present as well as how they are combined in the substance • Two main types are: • Pure Substances • Mixtures

7. MIXTURE yes no Is the composition uniform? Types of mixtures flowchart MATTER yes no Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture (suspension)

8. Mixtures • Mixtures • Are physical combinations of different substances • Composition can vary (the proportions are not fixed) • Can be separated into original parts using physical changes

9. Mixtures • Homogeneous Mixture • has a uniform composition • will not settle out • also called a solution • Examples: salt water, Kool-Aid, air, steel, etc.

10. Mixtures • Heterogeneous Mixture • composition is not uniform • will settle out • also called a suspension • Examples: blood, orange juice, mud puddle, salad dressing, bird seed, etc.

11. Mixtures • Colloids (special type of heterogeneous mix.) • Particles are intermediate in size… larger than those in a solution and smaller than those in a suspension • will not settle out • particles cannot be filtered • can be distinguished by Tyndall effect where visible light is scattered (solutions don’t do this) • Examples: Jello, whipped cream, marshmallow, milk, smoke, etc.

12. What type of mixture is shown?

13. What type of mixture is shown?

14. What type of mixture is shown?

15. What type of mixture is shown?

16. Ways to separate mixtures • Separating mixtures is just problem-solving… • One looks at the different physical properties of the substances in a mixture and selects one that is different • Examples: distillation, filtration, decantation, evaporation, chromatography, centrifugation, electrophoresis

17. Distillation • Purpose: used when boiling points differ between substances in a mixture • Process: liquid mixture is boiled to produce a vapor which is collected and condensed back into a simpler liquid

18. Filtration • Purpose: used when mixtures consist of liquids and solids together • Process: solid/liquid mixture is poured through a screen or filter to catch the solid particles while the liquid flows past

19. PURE SUBSTANCE yes no Can it be chemically decomposed? Types of pure substances flowchart MATTER yes no Can it be physically separated? Compound Element

20. Pure substances • Pure Substances • Composition consists of atoms in fixed proportions • Example: Water is H2O. It always has 2 hydrogens attached to 1 oxygen. • Cannot be broken down into simpler substances physically

21. Pure substances • Elements • simplest form of matter • consists of one type of atom • only substances on the periodic table • Example: gold (Au), aluminum (Al), carbon (C), etc.

22. Pure substances • Compounds • contains two or more elements chemically combined • is in fixed proportions (can be shown with a chemical formula) • cannot be broken down into simpler substances physically • Examples: H2O (water), NaCl (table salt), C6H12O6 (sugar), etc.

23. Ways to separate pure substances • To separate, chemical reactions must occur through a change in energy caused by chemical interactions, electricity, heat exchange, etc. • Example: Electrolysis of water • Direct current is applied to water (H2O) causing it to split into separate hydrogen atoms and oxygen atoms.

24. MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be chemically decomposed? Types of matter flowchart MATTER yes no Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture (suspension) Compound Element

25. Classifying matter by state • The focus is on the arrangement of atoms in a particular substance • 4 main states of matter are: • solid • liquid • gas • plasma • 2 other states include Bose-Einstein condensate and fermionic condensate

26. Solids • Definite shape • Definite volume • Not easily compressed

27. Liquids • Indefinite shape (it can flow) • Definite Volume • Not easily compressed

28. Gases • Indefinite shape • Indefinite volume • Easily compressed

29. Plasma • Indefinite shape • Indefinite volume • Particles become ionized (positive and negative charges) which allows electricity to flow through them