The Classification of Matter

1. The Classification of Matter Chapter 2

2. What is matter? • Matter is defined as anything that has mass and takes up space. • Mass is the measurable amount of matter (kg). • Volume is the amount of space that matter takes up (m3)

3. Weight vs. Mass • Weight is the measure of the gravitational pull on an object. • Do you weigh the same on Earth as you would on the moon? • If you weigh 100 lb. on Earth you would weigh 20.7 lb. on the Moon, 113.1 lb. on Venus or 47.1 lb. on Mars!

4. States of Matter • States of Matter • Solid - definite shape and volume • Liquid - takes shape of container but has definite volume • Gas - takes the shape and volume of its container • What determines the state of matter of a substance? Temperature & pressure

5. Law of Conservation of Matter • Matter can neither be created nor destroyed in any process

6. So what things are matter? • What were the items you listed as matter? • What isn’t matter? • Light, sound, thoughts, dreams (even though they sometimes seem real!)

7. Classification of Matter • Matter can be classified in a number of ways. • 1. Can it be separated by physical means? • If the answer is “no”, then it is a pure substance. • If the answer is “yes”, then it is a mixture

8. Pure Substance • A pure substance is a sample of matter with unique chemical and physical properties that cannot be physically separated. • A substance and a pure substance are the same thing.

9. Classification of Substances • Can the pure substance be chemically separated? • Yes: then it is a compound • No: then it is an element

10. Element • An element is a single atom with unique number of protons. (Pb, Hg, Po) • No two elements have the same number of protons • The number of protons (Atomic Number) defines “who” an element it. • Each element is represented by a unique symbol • The smallest unit of an element is an atom.

11. Compound • A compound is a combination of 2 or more elements. (CH4, N2O2) • A compound is represented by a formula which are the symbols of the element with a subscript indicating the number of elements (H2O) • Each formula is exclusive to a compound. • The smallest unit of a compound is a molecule.

12. Law of Definite Proportions • Every pure substance always contains the same elements combined in the same proportions by weight. • i.e. elements combine in simple, small, whole number ratios to form unique chemical compounds

13. Diatomic Molecules • There are 7 elements that must exist as diatomic molecules to be stable. (2 atoms) • Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, Iodine • H2, N2, O2, F2, Cl2, Br2, I2 • These are molecules, not elements • There are 7, they start at 7 (Nitrogen is Atomic Number 7), and they make a 7! (but you also have to add Hydrogen)

14. Allotrope • An allotrope is an element that has different structural forms. • Carbon: Diamond, Graphite, Buckyball (C60)

15. Mixtures • If a sample of matter can be physically separated, then it is a mixture. • The components of a mixture retain their own properties (Ice + Tea; ice is still a solid, tea is still a liquid, together they are iced tea) • Is the mixture uniform? • Yes: Homogeneous • No: Heterogeneous

16. Examples? • What are some examples of a homogeneous mixture? • Kool-aid, Tap Water, Air • What are some examples of a heterogeneous mixture? • Kool-aid on Ice, Salad, Smoky Air

17. Separating Mixtures • A mixture can be physically separated. • Decanting • Filtration • Centrifugation • Distillation (and Fractional Distillation) • Physical Manipulation (sorting) • Evaporation • Crystallization • Chromatography

18. Decanting • Decanting is a way to separate a solid and liquid by pouring off the liquid without disturbing the solid. • Example: pouring off the saltwater from a bucket of sand from the surf.

19. Filtration • Filtration is a way to separate an insoluble solid from a liquid. The solid remains in the filter paper and the liquid goes through the paper into the beaker. • Example: A seine net filters the fish out of the ocean.

20. Centrifugation • Centrifugation is a method to separate substances with different densities using centripetal forces. • Example: separating white blood cells, plasma and red blood cells

21. Distillation • Distillation is a method to separate liquids with different boiling points or to separate the liquid from a solution. The solution is heated in a flask until the liquid boils. The vapor produced passes into the condenser where it is cooled and condenses to a liquid. The pure liquid (distillate) is collected in a beaker. • Example: saltwater purification

22. Physical Sorting • Physical sorting is a hand manipulated method to separate solids. • Example: sorting a bin of bouncy balls into small, medium and giant bouncy balls.

23. Evaporation • Evaporation is a method for separate a soluble solid from a liquid. If the solution is heated, the liquid evaporates leaving the solid behind. • Example: boiling a pan of saltwater and leaving the crystalline NaCl behind

24. Crystallization • Crystallization is a method of separation in which a chemical compound, dissolved in a given solvent, precipitates under certain conditions to allow separation between the phases. • Example: making rock candy from sugar on a string

25. Chromatography • Chromatography is a separation science based on the affinity of the compound to the mobile phase (solvent). If the compound is very soluble, it will separate easily and faster. • Example: separating ink on paper

26. Classify each of the following as element, compound or mixture. If it is a mixture, determine how you would separate it. Ocean water blood soil ethyl alcohol calcium carbonate air gasoline sucrose You Decide!

27. Physical & Chemical Properties and Changes

28. Properties • A Physical property is one that describes a sample of matter using the 5 senses • Smell • Touch • Taste • Sound • Sight • A Chemical property is one that describes the relative ability of a substance to participate in a reaction.

29. Examples • Density is a physical property because it describes how much space an amount of matter occupies. • Reactivity is a chemical property that describes how a substance can cause an explosion or other violent reaction.

30. Changes take place . . . • A Physical change is simply one that changes the physical property, but the identity of the substance remains the same. • Ice is solid H2O, but Water is liquid H2O • A Chemical change is any process that results in a new chemical • Baking soda plus vinegar makes CO2 and sodium acetate.

31. How do I know if there is a chemical change? • There are four (4) indicators that a chemical change may have taken place • Evolution of a gas. (this includes odor) • Exchange of heat (hot or cold) • Formation of a precipitate. • Color Change

32. How can I really know? • The only way to truly know if you have formed a new chemical is to analyze the product to determine it’s identity.

33. Write down these reactions and leave a space for observations. • Copper (Zinc) and Hydrochloric Acid • Magnesium and Oxygen • Bromothymol Blue and Acid • Ammonium nitrate and Water • Copper and Silver Nitrate • Methane and Oxygen • Decomposition of Nitrogen triiodide • Hydrolysis of water • Underwater Fireworks • Phosphorescence