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Unit 2 Matter and Change

Unit 2 Matter and Change. Chemistry I Mr. Patel SWHS. Topic Outline. Continue to Learn Major Elements and Symbols Properties of Matter (2,1, 2,2, 2,3) Physical and Chemical Changes (2.1, 2.4) Inter-/Intra-molecular Forces States of Matter (13.2, 13.2, 13.3)

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Unit 2 Matter and Change

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  1. Unit 2Matter and Change Chemistry I Mr. Patel SWHS

  2. Topic Outline Continue to Learn Major Elements and Symbols Properties of Matter (2,1, 2,2, 2,3) Physical and Chemical Changes (2.1, 2.4) Inter-/Intra-molecular Forces States of Matter (13.2, 13.2, 13.3) Kinetics/KMT, Phase Change (13.1, 13.4)

  3. Properties of Matter Remember matter is anything that has mass and occupies volume. Matter is described using properties that are extensive or intensive properties.

  4. Extensive Properties • Extensive Property – a property that depends on the amount of matter in a sample. (Changes with amount) • Mass – measure of the amount of matter an object contains • Volume – measure of the space taken up • Other examples: energy, weight, length, area

  5. Intensive Properties • Intensive Property – a property that does NOT depend on the amount of matter • Density – D = mass/volume matter per unit volume • Other examples: hardness, melting/freezing point, concentration, viscosity

  6. Classify the statement as Intensive or Extensive • The Boiling point of water is 100OC. • The mass if 300 kg. • The length is 30 m. • The density of water is 1.0 g/mL. • Intensive • Extensive • Extensive • Intensive

  7. Substance All matter can be divided into substances and mixtures Substance – uniform and definite composition Every sample of a substance has identical intensive properties. Why?

  8. CopperKettle Gold Sculpture

  9. MatterAnything that has mass and volume SubstanceConstant Composition; All particles identicalEx: Water, Helium MixtureVariable Composition; 2 or more substancesEx: Sand, Soil Physically Separate

  10. Substances • Substances can be classified as elements or compounds • Element – simplest form of matter with unique set of properties (all atoms same) • Ex: Gold, Hydrogen, Oxygen (on periodic table) • Compound – two or more elements chemically combined in fixed ratios • Ex: Water, salt, baking soda • Compounds can be chemically separated to elements

  11. MatterAnything that has mass and volume SubstanceConstant Composition; All particles identicalEx: Water, Helium MixtureVariable Composition; 2 or more substancesEx: Sand, Soil Physically Separate ElementMade up of identical atoms; on Periodic TableEx: Zinc, Uranium CompoundMade up of 2 or more elements; combined chemicallyEx: Carbon dioxide Chemically Separate

  12. Mixtures • Mixture – a physical blend of two or more components (substances) • Heterogeneous Mixture – the composition is not uniform throughout • Ex: soil, chicken noodle soup • Homogeneous Mixture – (solution) composition is uniform throughout • Ex: salt water, alloys (solid in solid)

  13. Mixtures Mixtures can be separated physically Filtration – solid from liquid Distillation – liquid from liquid or solid

  14. Steel = Iron + Carbon

  15. MatterAnything that has mass and volume SubstanceConstant Composition; All particles identicalEx: Water, Helium MixtureVariable Composition; 2 or more substancesEx: Sand, Soil Physically Separate ElementMade up of identical atoms; on Periodic TableEx: Zinc, Uranium CompoundMade up of 2 or more elements; combined chemicallyEx: Carbon dioxide HeterogeneousUneven Distribution; easy to separateEx: Vegetable Soup HomogenousUniform Distribution; called solutionEx: Tap water, Steel Chemically Separate

  16. Physical Changes and Properties • Physical Property – measured properties that do not change the nature of the sample • Ex: Boiling Point, Density, Mass • Physical Change – some properties may change but the composition of the material does not change • Ex: Boiling, Freezing, Cutting, Splitting • Can be Reversible or Irreversible

  17. Physical Changes and Properties • Physical Changes do not involve chemical reactions • No Breaking or Forming Chemical Bonds • Substance is the same before and after the change

  18. Chemical Changes & Properties • Chemical Property – the ability of a substance to undergo a chemical reaction • Ex: Flammability, Combustibility, decomposition • Chemical Change – the composition of matter will always change • Ex: Burning, exploding, reacting, rusting, rotting • Also called a chemical reaction

  19. Signs of Chemical Changes • Clues for a chemical reaction: • Transfer of Energy – heat, sound, light • Color Change • Gas Production • Formation of Precipitate – solid that settles out of a liquid mixture • Don’t confuse for a physical change

  20. Conservation of Mass Law of Conservation of Mass – mass is neither created nor destroyed; it is only transformed. The mass before a reaction must always equal the mass after a reaction

  21. Classify: Physical or Chemical Change • Burning Gasoline • Evaporation of Water • Stripping a Copper Wire • Mold Growing on Yogurt • Alka-Setlzer tablets • Chemical • Physical • Physical • Chemical • Chemical

  22. Molecular Forces INterMolecular Forces Intramolecular forces • Forces between individual molecules • Strong by Numbers • Ex: Hydrogen Bonding, Dipole forces, Dispersion Forces • Contribute to Physical Changes • Forces within a specific, individual molecule • Very Strong • Ex: Ionic Bond, Covalent Bond, Metallic Bond • Contribute to Chemical Changes

  23. States of Matter • There are four states of matter • Solid • Liquid • Gas • Plasma • We focus mostly on the first three

  24. Solids • Definite Shape • Definite Volume • Incompressible • Particles tightly packed - ordered • Vibrations (Not Fluid)

  25. Liquids • Indefinite Shape • Definite Volume • Incompressible • Particles in contact but disorderly packed • Particles flow (Fluid)

  26. Gases • Indefinite Shape • Indefinite Volume • Highly Compressible • Particles far apart; little contact; collisions • Particles flow (Fluid)

  27. Gases • Particles: • Have a lot of space between them • Are in rapid motion • Exert Pressure = Billions of collisions • Spontaneously expands

  28. Phase Changes There are 6 state/phase changes Some change require heat (energy) Endothermic – requires heat Exothermic – releases heat

  29. 1. Melting • Solid to Liquid • Endothermic • Particles have enough energy to begin to flow • Melting Point – temp when liquid forms

  30. 2. Freezing • Liquid to Solid • Exothermic • Particles have lose energy and slow down • Freezing Point – temp when Solid forms • Mpt = Fpt

  31. 3. Boiling • Liquid to Gas • Endothermic • Particles have enough energy to break away • Boiling Point – temp when gas forms

  32. 4. Condensation • Gas to Liquid • Exothermic • Particles begin to stick • Same as Bpt

  33. 5. Sublimation • Solid to Gas • Endothermic • NO liquid stage • Ex: Dry Ice

  34. 6. Deposition • Gas to Solid • Exothermic • No Liquid Stage • Ex: Snowing

  35. Temperature and Pressure The temperature at which a substance undergoes a phase change depends on the pressure. Think about boiling an egg on top of Mt. Everest. Pressure is lower so water boils at a lower temperature meaning it will take longer to cook the egg (enough heat)

  36. Phase Diagrams A Phase Diagram outlines the relationship between temp and pressure. At a specified temp and pressure, we can determine what state of matter the substance is in.

  37. Phase Diagrams There are two important points Triple Point – where solid, liquid, gas coexist Critical Point – no phase boundary exist Each line represents two states coexisting

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