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Chemistry I Mr. Patel SWHS
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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)
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Remember matter is anything that has mass and occupies volume. Matter is described using properties that are extensive or intensive properties.
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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
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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
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1. The Boiling point of water is 100 O C. 2. The mass if 300 kg. 3. The length is 30 m. 4. The density of water is 1.0 g/mL. 1. Intensive 2. Extensive 3. Extensive 4. Intensive
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All matter can be divided into substances and mixtures Substance – uniform and definite composition Every sample of a substance has identical intensive properties. Why?
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Copper Kettle
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Matter Anything that has mass and volume Substance Constant Composition; All particles identical Ex: Water, Helium Mixture Variable Composition; 2 or more substances Ex: Sand, Soil Physically Separate
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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
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Matter Anything that has mass and volume Substance Constant Composition; All particles identical Ex: Water, Helium Mixture Variable Composition; 2 or more substances Ex: Sand, Soil Element Made up of identical atoms; on Periodic Table Ex: Zinc, Uranium Compound Made up of 2 or more elements; combined chemically Ex: Carbon dioxide Physically Separate Chemically
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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)
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Mixtures can be separated physically Filtration – solid from liquid Distillation – liquid from liquid or solid
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Steel = Iron + Carbon
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Matter Anything that has mass and volume Substance Constant Composition; All particles identical Ex: Water, Helium Mixture Variable Composition; 2 or more substances Ex: Sand, Soil Element Made up of identical atoms; on Periodic Table Ex: Zinc, Uranium Compound Made up of 2 or more elements; combined chemically Ex: Carbon dioxide Physically Separate Chemically Heterogeneous Uneven Distribution; easy to separate Ex: Vegetable Soup Homogenous Uniform Distribution; called solution Ex: Tap water, Steel
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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
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Physical Changes do not involve chemical reactions No Breaking or Forming Chemical Bonds Substance is the same before and after the change
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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
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Clues for a chemical reaction: 1. Transfer of Energy – heat, sound, light 2. Color Change 3. Gas Production 4. Formation of Precipitate – solid that settles out of a liquid mixture Don’t confuse for a physical change
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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
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1. Burning Gasoline 2. Evaporation of Water 3. Stripping a Copper Wire 4. Mold Growing on Yogurt 5. Alka-Setlzer tablets 1. Chemical 2. Physical 3. Physical 4. Chemical 5. Chemical
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INTERMOLECULAR FORCESINTRAMOLECULAR 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
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There are four states of matter 1. Solid 2. Liquid 3. Gas 4. Plasma We focus mostly on the first three
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Definite Shape Definite Volume Incompressible Particles tightly packed - ordered Vibrations (Not Fluid)
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Indefinite Shape Definite Volume Incompressible Particles in contact but disorderly packed Particles flow (Fluid)
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Indefinite Shape Indefinite Volume Highly Compressible Particles far apart; little contact; collisions Particles flow (Fluid)
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Particles: Have a lot of space between them Are in rapid motion Exert Pressure = Billions of collisions Spontaneously expands
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There are 6 state/phase changes Some change require heat (energy) Endothermic – requires heat Exothermic – releases heat
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Solid to Liquid Endothermic Particles have enough energy to begin to flow Melting Point – temp when liquid forms
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Liquid to Solid Exothermic Particles have lose energy and slow down Freezing Point – temp when Solid forms Mpt = Fpt
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Liquid to Gas Endothermic Particles have enough energy to break away Boiling Point – temp when gas forms
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Gas to Liquid Exothermic Particles begin to stick Same as Bpt
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Solid to Gas Endothermic NO liquid stage Ex: Dry Ice
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Gas to Solid Exothermic No Liquid Stage Ex: Snowing
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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)
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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.
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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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