Lesson # 2.1: Properties of Matter Unit # 2 Matter, Energy, and Change OBJECTIVES: Identify properties of matter as extensive or intensive. Classify properties as Physical or Chemical Differentiate among three states of matter. Describe a physical change. Matter Anything that: a) has mass, and b) takes up space Mass = a measure of the amount of stuff (or material) the object contains. Volume = a measure of the space occupied by the object Physical States of Matter All matter is made of tiny particles. The type and arrangement of particles determine the properties of the matter. Most of matter samples are in one of three physical states. 4 Physical States of matter 1. Solid- matter that can not flow (definite shape) and has definite volume. 2. Liquid- definite volume but takes the shape of its container (flows). 3. 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. (Which is correct: water gas, or water vapor?) States of Matter Solid Liquid Gas Definite Volume? Definite Shape? Result of a Temperature Increase? Small Small Large Will it Compress? 1
4 th state: Plasma - formed at high temperatures; ionized phase of matter as found in the sun Microscopic View of the Three Main Phases Energy determines the state! Freeze Melt Add Heat Condense Evaporate Deposition Sublimation Solid Liquid Gas Remove Heat Copper Phases - Solid Copper Phases - Liquid 2
Copper Phases Vapor (gas) Describing Matter Properties are used to describe matter Properties are words (adjectives) that describe the appearance and/or behavior of matter Describing Matter Properties can be classified as: 1) Extensive depends on the amount of matter in the sample - Mass, volume, calories are examples 2) Intensive depends on the type of matter, not the amount present - Hardness, Density, Boiling Point Properties can be classified as Physical Properties- can be observed and measured without changing the material s composition. Ex.- color, hardness, m.p., b.p. Chemical Properties- can only be observed by changing the composition of the material. Ex.- ability to burn, decompose, ferment, react with, inert, etc. Physical vs. Chemical Change Physical change Changes the visible appearance, without changing the composition of the material. Boil, melt, cut, bend, split, crack Can be reversible (freeze, boil), or irreversible (break, grind) Physical vs. Chemical Change (Cont.) Chemical change - The atoms in the substance are rearranged into one or more new substances. During a chemical change the composition of matter always changes. A chemical change s also called a chemical reaction. Ex: Rust, burn, decompose, ferment 3
Examples For You! More Examples For You! 19 20 Chemical Change Heat and light are often evidence of a chemical change. The Players in a Chemical Reaction Reactants- the stuff you start with Products- what you make The products will have NEW PROPERTIES different from the reactants you started with Arrow points from the reactants to the new products Recognizing Chemical Changes 1) Energy is absorbed or released (temperature changes hotter or colder) 2) Color changes 3) Odor changes 4) Gas production (bubbling, fizzing, smoke) 5) formation of a precipitate - a solid that separates from solution (won t dissolve) 6) Irreversibility - not easily reversed But, there are examples of these that are not chemical boiling water bubbles, etc. The Law of Conservation Nature is a miserly accountant -Richard Dawkins During any chemical reaction, the total mass of the products is always equal to the total mass of the reactants. The Law of Conservation of mass- Matter can not be created or destroyed, only changed. 24 4
Consequences of Conservation 43.43 g Original mass = 43.43 g Final mass reactants = product 25 What is mind? Does it matter? What is matter? Never mind! Any Questions? Bertrand Russell 1872-1970 27 5