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The Classification of Matter

The Classification of Matter. Chapter 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 (m 3 ). Weight vs. Mass.

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The Classification of Matter

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  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

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