Chemistry I Mr. Patel SWHS 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) Remember matter is anything that has mass and occupies volume. Matter is described using properties that are extensive or intensive 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 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 1. The Boiling point of water is 100OC. 1. Intensive 2. The mass if 300 kg. 2. Extensive 3. The length is 30 m. 3. Extensive 4. The density of water is 1.0 g/mL. 4. Intensive All matter can be divided into substances and mixtures Substance – uniform and definite composition Every sample of a substance has identical intensive properties. Why? Matter Anything that has mass and volume Substance Constant Composition; All particles identical Ex: Water, Helium Mixture Physically Separate Variable Composition; 2 or more substances Ex: Sand, Soil 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 Matter Anything that has mass and volume Substance Mixture Constant Composition; All particles identical Ex: Water, Helium Element Made up of identical atoms; on Periodic Table Ex: Zinc, Uranium Physically Separate Compound Chemically Separate Made up of 2 or more elements; combined chemically Ex: Carbon dioxide Variable Composition; 2 or more substances Ex: Sand, Soil 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) Mixtures can be separated physically Filtration – solid from liquid Distillation – liquid from liquid or solid Steel = Iron + Carbon Matter Anything that has mass and volume Substance Mixture Constant Composition; All particles identical Ex: Water, Helium Element Made up of identical atoms; on Periodic Table Ex: Zinc, Uranium Physically Separate Compound Chemically Separate Made up of 2 or more elements; combined chemically Ex: Carbon dioxide Variable Composition; 2 or more substances Ex: Sand, Soil Heterogeneous Homogenous Uneven Distribution; easy to separate Ex: Vegetable Soup Uniform Distribution; called solution Ex: Tap water, Steel 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 Physical Changes do not involve chemical reactions • No Breaking or Forming Chemical Bonds • Substance is the same before and after the change 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 Clues for a chemical reaction: 1. 2. 3. 4. 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 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 1. 2. 3. 4. 5. Burning Gasoline Evaporation of Water Stripping a Copper Wire Mold Growing on Yogurt Alka-Setlzer tablets 2. Chemical Physical 3. Physical 4. Chemical 5. Chemical 1. INTERMOLECULAR FORCES Forces between individual molecules Strong by Numbers Ex: Hydrogen Bonding, Dipole forces, Dispersion Forces Contribute to Physical Changes INTRAMOLECULAR FORCES Forces within a specific, individual molecule Very Strong Ex: Ionic Bond, Covalent Bond, Metallic Bond Contribute to Chemical Changes