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Chapter 1 – Matter and Change
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1-1 Chemistry Is a Physical Science Chemistry – study of composition, structure and properties of matter and changes matter undergoes Matter is…
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1-1 Branches of Chemistry OrganicInorganicPhysicalAnalyticalBiochemistryTheoretical
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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
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1-1 Basic Research v. Applied Research Basic Research – for the sake of increasing knowledge Applied Research – to solve a problem
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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)
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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.
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Compounds can be very simple or very complex. synthetic molecule that mimics a protein found on the surface of T- cells ammonia
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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.
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1-2 Properties of Matter Physical Property – characteristic that can be observed without changing identity of substance Ex.
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1-2 Physical Changes Do not involve a change in the identity of a substance Examples -
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1-2 Properties of Matter Change of state is a PHYSICAL change solid liquidgas
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1-2 Properties of Matter stateShapeVolumeenergymotionspacing solid liquid gas
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1-2 Chemical Properties Chemical Property relates to substance’s ability to undergo changes that transform it into different substances Examples -
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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
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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
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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).
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Exothermic vs. Endothermic Reactions exothermic reaction reaction endothermic reaction
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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
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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
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1-2 Mixtures homogeneous – uniform in composition – same proportion of components throughout (also called solutions) heterogeneous – not uniform throughout – has distinct PHASES
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Mixtures: Milk
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Mixtures: Granite
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Mixtures: salt water
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1-2 Mixtures Can be separated by PHYSICAL means FiltrationDistillationCentrifugationChromatography
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filtration
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distillation
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centrifugation
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chromatography
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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)
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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)
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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
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1-3 Elements periodic table is an arrangement of elements Each square represents an element – name, chemical symbol, atomic number, average atomic mass
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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)
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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
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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
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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
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