Transcript File
UNIT 1 PART ONE: Matter and Change 1 What is Chemistry 2 Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes. What is everything made of? What characteristics or properties make matter what it is? What properties do all matter have in common? 3 What is Matter? Matter is anything that takes up space and has mass. This is too much to handle Needs to be broken down into categories and subcategories. 4 Matter Flowchart Matter Pure Substances 5 Mixtures Mixtures Mixtures Homogeneous 6 Heterogeneous Mixtures Mixtures are a physical blending of two or more pure substances. They have variable composition. A Heterogeneous mixture is not uniform in composition, it has more than one phase. Ex: Oil in water, Chocolate chip cookie, gravel, soil, milk. 7 Mixtures A Homogeneous mixture is uniform throughout, a single phase. Ex: Kool-aid, air, salt water. Another name for homogenous mixture is solution. Every part of the mixture keeps its own properties. 8 Pure Substances Pure Substances Elements 9 Compounds Building Blocks of Matter An element is a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom. A compound is a substance that can be broken down into simpler, stable substances. Each compound is made from the atoms of two or more elements that are chemically bonded. 10 Pure Substances vs Mixtures Have a fixed composition and differs from a mixture in the following ways: 1. All samples of a pure substance have the same characteristic physical and chemical properties. 2. Every sample of a given pure substance has exactly the same composition, such as all water molecules contain, 11.2% hydrogen, 88.8% oxygen. 11 Properties and Changes in Matter Extensive Properties depends on the amount of matter that is present. Ex: – Volume – Mass – Amount of energy in the substance 12 Properties and Changes in Matter Intensive Properties do not depend on the amount of matter present. Ex: – Melting point – Boiling point – Density – Ability to conduct electricity – Ability to transfer energy as heat 13 Properties 14 Physical Properties are properties that can be observed and measured without changing the substance. – cutting, grinding, dissolving, shrinking or expanding. Properties Chemical Properties are properties that can only be observed by changing the type of substance. A chemical reaction takes place and new substances are produced. – Ability to sustain fire, flammability, can neutralize a base, 15 States of matter Solid- matter that can not flow, has a definite shape and has definite volume. Liquid- definite volume but takes the shape of its container (flows). Gas- a substance without definite volume or shape and can flow. » Vapor- a substance that is currently a gas but normally is a liquid or solid at room temperature. 16 States of Matter Expansion w/ Temp. increase Compressible? YES Small Expans. NO NO Small Expans. NO NO Large Expans. YES Definite Definite Volume? Shape? Solid Liquid Gas 17 YES YES NO Condense Freeze Evaporate Melt Solid 18 Liquid Gas States of Matter There are more Plasma – high temperature low pressure – electrons separate from nucleus – Most common in the universe More at very low temp – Bose- Einstein condensate – Quantum superfluids 19 Another Way to Change States Pressure For some substances it will turn solids to liquids – Lake under Antarctica For others it will turn liquids to solids – Silly putty – Dry Ice Will turn gas to liquid – Compressor in refrigerator and AC 20 Physical Changes A change that changes appearances, without changing the composition. Examples? – Change of size – Change of state: solid liquid gas – Grinding 21 Chemical Changes Chemical changes - a change where a new form of matter is formed. Also called chemical reaction. Reactant(s) Product(s) Not phase changes – Ice is still water. 22 Chemical Reactions When one or more substances are changed into new substances. Reactants- stuff you start with Products- What you make NEW PROPERTIES Because each substance has its own properties 23 Indications of a chemical reaction Temperature absorbed or released Gas produced Color change Odor change Precipitate- solid that separates from solution, cloudy appearance Light emitted or absorbed ONLY CLUES NOT CERTAINTY! 24