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

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

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)

Separation Techniques Filtration- solid part is trapped by filter paper and the liquid part runs through the paper Vaporization- where the liquid portion is evaporated off to leave solid

Separation Techniques Decanting- when liquid is poured off after solid has settled to bottom Centrifuge- machine that spins a sample very quickly so that components with different densities will separate

Separation Techniques Paper Chromatography- used to separate mixtures because different parts move quicker on paper than other

1.3 Elements

Elements elements are pure substances organized by properties on periodic table each square shows the name and letter symbol for each element usually the symbols relate to the English names but some come from older names (usually Latin) Ex: gold’s symbol is Au from aurum Ex: iron’s symbol is Fe from ferrum

Periodic Table Groups Periods also called families vertical columns numbered 118 have similar chemical properties Periods horizontal rows properties changes consistently across a period

Periodic Table

Periodic Table two rows below the periodic table are the lanthanide and actinide series these rows fit after #57 and #89 they are only at the bottom to keep the width of the chart smaller

Types of Elements Metals an element that is a good conductor of electricity at room temperature, most are solids malleable- can be rolled or hammered into sheets ductile- can be made into wire high tensile strength- can resist breakage when pulled most have silvery or grayish white luster

Types of Elements Nonmetals an element that is a poor conductor of heat and electricity many are gases at room temperature some are solids: usually brittle, not malleable

Types of Elements Metalloids an element that has some characteristics of metals and nonmetals appear along staricase line B, Si, Ge, As, Sb, Te all are solids at room temperature less malleable that metals but less brittle than nonmetals are semiconductors

Types of Elements Noble Gases generally unreactive gases in far right column of periodic table