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Introduction to Chemistry What Matters? Chapters 2 & 3 SI Units • • • • • • Length – meter Mass – kilogram Time – second Temperature – Kelvin Quantity of Matter – mole Volume - liter Commonly Used Prefixes • Centi- 1/100 or 0.01 • Kilo1000 or 1.0 x 103 • Milli1/1000 or 0.001 Matter • Def- anything that has mass and occupies space • 3 States of matter – Solid – Liquid – Gas Phase Changes • • • • • • Melting Freezing Vaporization/Evaporation Condensing Sublimation Deposition Changes of State Melting/Freezing • Energy must be ADDED for a substance to melt • Energy must be REMOVED for a substance to freeze Vaporization & Condensation • Energy must be ADDED for a substance to boil • Energy must be REMOVED for a substance to condense Deposition/Sublimation • Energy must be added for a substance to sublime • Energy must be removed for a substance to undergo deposition Law of Conservation of Energy • Energy cannot be created or destroyed • Energy of a reaction MUST be conserved Elements, Compounds & Mixtures Elements • An element is matter in its simplest form • Cannot be broken down by chemical means • Periodic Table (114 elements) Compounds • Are combinations of elements • Have the same composition • Can be broken down by chemical means Mixtures • Have variable composition • Can be separated physically or chemically • Homogeneous Mixtures – are the same throughout • Heterogeneous Mixtures – have different regions Law of Conservation of Matter • Matter cannot be created or destroyed • Mass of a chemical reaction MUST be conserved Separatory Techniques Filtration • Used for separating undissolved solids • Pour through a mesh (filter paper) Distillation • Used to separate dissolved solids or liquid mixtures • Uses physical changes Chromatography • Uses chemicals to separate the pigments of plant or chemicals • Various Methods – Gas chromatography – Liquid chromatography – Thin-layer chromatography – Ion-exchange chromatography Chemical vs Physical Physical Properties • A set of characteristics unique to a substance • • • • • • • Odor Color Volume State Density Boiling point Melting point Chemical Properties • The ability of a substance to form new substances • • • • Wood burning Iron rusting Digestion photosynthesis Physical Change • Does NOT change the identity of the substance • Composition remains the same Chemical Change • Changes the composition of the substance • Has new physical properties that differ from the original
