1.2 Matter and Its Properties Ch. 1: Matter and Change 1.2 Matter and Its Properties

Terms Matter- anything that has mass and volume Atom- smallest unit of an element that keeps the properties of element Element- pure substance made of only one type of atom Compound- substance made of 2 or more types of atoms that are chemically bonded Molecule- type of compound in which bonds are covalent bonds

Properties of Matter chemists use characteristic properties to tell substances apart and to separate them some properties define a group of substances

Types of Properties Extensive- depend on the amount of matter Ex: volume, mass, amount of energy Intensive- do not depend on the amount Ex: density, boiling point, ability to conduct

Types of Properties Physical- characteristics that can be observed or measured without changing the identity of a substance Chemical- relates to a substances ability to undergo changes that transform it into a different substance Easiest to see when a chemical is reacting

Physical Changes in Matter Includes all changes of state (physical changes of a substance from one state to another) change in a substance that doesn’t change the identity of the substance Ex. grinding, cutting, melting, boiling

Solid definite volume definite shape atoms are packed together in fixed positions strong attractive forces between atoms only vibrate in place

Liquid definite volume indefinite shape atoms are close together atoms can overcome attractive forces to flow

Gases indefinite volume indefinite shape atoms move very quickly atoms are far apart pretty weak attractive forces

Changes of State

Plasma high temperature state in which atoms lose their electrons Ex. the sun

Chemical Changes in Matter a change in which a substance is converted into a different substance same as chemical reaction doesn’t change the amount of matter present reactants- substances that react products- substances that form

mercury + iodine  mercuric iodide

Energy Changes in Matter when any change occurs, energy is always involved energy can be in different forms (light, heat, etc.) energy is never destroyed or created (law of conservation of energy)

Energy Changes in Matter Exothermic Reaction- reaction that gives off energy (feels warm on outside) Endothermic Reaction- reaction that uses up energy (feels cold on outside)

Go on to Classification of Matter