Chapter 1 – Matter and Change

1-1 Chemistry Is a Physical Science Chemistry – study of composition, structure and properties of matter and changes matter undergoes Matter is…

1-1 Branches of Chemistry OrganicInorganicPhysicalAnalyticalBiochemistryTheoretical

1-1 Chemicals What is a chemical? A chemical is any substance that has definite composition Caffeine always has 8 carbon atoms, 10 hydrogen atoms, 4 nitrogen atoms, and 2 oxygen atoms Caffeine, C 8 H 10 N 4 O 2

1-1 Basic Research v. Applied Research Basic Research – for the sake of increasing knowledge Applied Research – to solve a problem

1-2 Matter and Its Properties Matter has mass and volume (takes up space) Mass – a measure of the amount of matter Volume – the space occupied by matter Density – the ratio of mass to volume (D=m/V)

1-2 Basic Building Blocks of Matter Atom – the smallest unit of an element that retains the properties of that element Element – pure substance made of only one kind of atom ex. Compound – substance made from atoms of 2 or more elements that are chemically bonded ex. ex.

Compounds can be very simple or very complex. synthetic molecule that mimics a protein found on the surface of T- cells ammonia

1-2 Properties of Matter Properties – characteristics, can help reveal identity of substance Extensive Properties – depend on the amount of matter present Ex. Intensive Properties – do not depend on the amount of matter present Ex.

1-2 Properties of Matter Physical Property – characteristic that can be observed without changing identity of substance Ex.

1-2 Physical Changes Do not involve a change in the identity of a substance Examples -

1-2 Properties of Matter Change of state is a PHYSICAL change solid liquidgas

1-2 Properties of Matter stateShapeVolumeenergymotionspacing solid liquid gas

1-2 Chemical Properties Chemical Property relates to substance’s ability to undergo changes that transform it into different substances Examples -

1-2 Chemical Changes Chemical change – one or more NEW SUBSTANCES are formed – also called chemical reaction Reactants – starting materials (substances that react) Products – substances formed by reaction

1-2 Chemical Changes Represented by chemical equations Word equation – names of reactants and products in words, + and  are used Ex. carbon + oxygen  carbon dioxide mercury (II) oxide  mercury + oxygen

1-2 Energy and Changes in Matter Energy is always involved in physical and chemical changes. Energy can be absorbed or released. Energy is never created or destroyed (conserved).

Exothermic vs. Endothermic Reactions exothermic reaction reaction endothermic reaction

1-2 Classification of Matter All matter is either a PURE SUBSTANCE or a MIXTURE pure substance – an element or compound mixture – contains more than one substance

1-2 Mixtures mixture – blend of 2 or more kinds of matter, each retaining its own identity and properties parts of mixture combined PHYSICALLY composition of a mixture is VARIABLE

1-2 Mixtures homogeneous – uniform in composition – same proportion of components throughout (also called solutions) heterogeneous – not uniform throughout – has distinct PHASES

Mixtures: Milk

Mixtures: Granite

Mixtures: salt water

1-2 Mixtures Can be separated by PHYSICAL means FiltrationDistillationCentrifugationChromatography

filtration

distillation

centrifugation

chromatography

1-2 Pure Substances Fixed composition, every sample has same characteristic properties, every sample has the same composition Ex. water, H 2 O, ALWAYS 2 hydrogen to 1 oxygen, ALWAYS 11.2% hydrogen, 88.8% oxygen (by MASS)

1-2 Pure Substances Compounds can be separated into simpler substances by CHEMICAL means – a chemical reaction must be carried out ex. water  hydrogen + oxygen (electrolysis) sugar  carbon + water sugar  carbon + water(heat)

1-2 Lab Chemicals and Purity All chemicals have some impurities even though lab chemicals usually treated as if pure Chemical grades of purity – different uses require different levels of purity More pure = more expensive

1-3 Elements periodic table is an arrangement of elements Each square represents an element – name, chemical symbol, atomic number, average atomic mass

1-3 Elements Naming – no one system – place (Cf), person (Md), property (Ra), source (Li), appearance (Hg), numbered (Uuu), some too old to trace (gold, iron, zinc) Chemical symbols – don’t always come from English name, sometimes Latin or other language (Na, Ag, Au, Pb, Cu)

1-3 Periodic Table Vertical columns – groups or families – similar chemical properties – 18 groups, numbered L to R Horizontal rows – periods - physical and chemical properties change across period 2 rows below table – lanthanides and actinides – put down there so table is not too wide

1-3 Types of Elements Metals – luster, conductivity, malleability, ductility, tensile strength – left side of periodic table Nonmetals – gases or brittle solids at RT, poor conductivity (insulators) - right side of periodic table

1-3 Types of Elements Metalloids – elements on border – have some characteristics of metals and some of nonmetals – semiconductors Noble Gases – unreactive, last to be discovered, gases at RT