2 Section 2.1 Matter Objectives Identify the characteristics of matter and substancesDifferentiate among the three states of matterDefine physical property and list several common physical properties of substances
3 Properties of Matter Matter anything that has mass and takes up space. The amount of matter the object contains.Note mass ≠ weight.SubstancePure substances contain only one kind of matter.Question – is lemonade a substance?
4 Physical PropertiesPhysical Property – a quality or condition of a substance that can be observed without changing the substance’s composition.Examples of physical properties are color, solubility, odor, hardness, density, melting point, and boiling point.
5 Properties of Solids, Liquids, Gases Has a definite shape and volumeDoes not depend on the shape of its containerAlmost incompressibleLiquidParticles are in close contact but not rigidly packedCan flow and take the shape of the container it is inA fixed volume can take a variety of shapes
6 Properties of Solids, Liquids, Gases Gas or vapor“Gas” is limited to those substances who are in a gaseous state at room temperature.“Vapor” describes the gaseous state of a substance that is a liquid or a solid at room temperature. An example is steam.Gases take the shape of the container they are in.Particles are spaced far apart.Gases expand without limit to fill any space, so its volume changes with the container, unlike liquids.Gases tend to expand when heated.
7 Physical ChangesA change which alters a given material without changing its composition is called a physical changeExamples are cutting, grinding, bendingMelting a metal, melting ice, boiling waterBoil, freeze, dissolve, melt, condense, break, split, crack – all examples of physical changes
8 Section 2.2 - Mixtures Objectives Categorize a sample of matter as a substance or a mixtureDistinguish between homogeneous and heterogeneous samples of matter
9 Classifying Mixtures Salad with lettuce, tomatoes, carrots A mixture is a physical blend of two or more substances.Salad with lettuce, tomatoes, carrotsBlood – with water, cells, chemicalsEach of these mixtures can vary in compositionHeterogeneous mixture – if you were to sample the mixture in two different places the composition wouldn’t be the same (salad)Homogeneous mixture – if you were to sample the mixtures in two different places, the composition would be the same (salt water)Homogeneous mixtures are called solutions.
10 Phases in MixturesSystemExamplesGas- gasCarbon dioxide and oxygen in nitrogen (air)Liquid – gasWater vapor in air (moist air)Gas – liquidCarbon dioxide in water (soda water)Liquid- liquidAcetic acid in water (vinegar)Solid – liquidSodium chloride in water (salt water or brine)Solid – solidCopper in silver (sterling silver, an alloy)Phase – any part of a system with uniform composition and properties is a phase.Homogeneous mixtures are one phase.Heterogeneous mixtures are two or more phases.Oil and vinegar separates into two phases
11 Separating MixturesSome mixtures can be separated by physical methods.Magnet to separate iron filings from sulfur.Distillation can be used to separate pure water from impurities.
12 Section 2.3 – Elements and Compounds ObjectivesExplain the difference between an element and a compound.Identify the chemical symbols of common elements, and name common elements given their symbols
13 Elements vs. CompoundsElements are the simplest forms of matter that can exist under normal laboratory conditions.This statement does not include the subatomic level (protons, neutrons, etc.)Elements cannot be separated into simpler substances by chemical means .Examples: Oxygen, carbon, nitrogenCompounds are made when two or more elements combine chemically, like H2O or CO2 .Compounds can be separated into simpler substances by chemical means.
14 CompoundsExample: Sodium chloride NaCl (table salt)Composed of Chlorine (which is the gas Cl2 as an element) and Sodium (which is the solid Na as an element)Anyone know why sodium (solid) is normally stored in oil?
15 Chemical Symbols Some chemical symbols are easy to remember Carbon = C, Oxygen = O, Nitrogen = NOthers are not so easy, and come from Latin or other sourcesSodium = Na (from Natrium)Potassium = K (from Kalium)Gold = Au (from Aurum)Lead = Pb (from Plumbum)A list of more unusual symbols is on page 40 and on my website for you to review!You will need to know at least the top 4 rows of the periodic table - name and symbol
16 Section 2.4 – Chemical Reactions ObjectivesDifferentiate between physical and chemical changes in matterApply the law of conservation of mass
17 Changing reactants to products Chemical reactions - one or more substances react and change into a new substanceExample: iron + oxygen = rust (iron oxide)The starting substances are called reactantsThe ending substances are called productsWords that convey that a chemical change has occurred include: burn, rot, rust, decompose, ferment, explode, corrode, etc.
18 Chemical PropertiesChemical properties tell you something about the ability of a substance to undergo a chemical reaction to form new substancesRusting is a chemical property of ironRotting is a chemical property of waste organic materialBurning is a chemical property of wood
20 Chemical reactions How can you tell if a reaction has taken place? Energy is always given off or absorbed during a reactionChange in color or odor –silver chromate forms when yellow sodium chromate is added to clear silver nitrate (above right)Production of gas or solid from a liquidzinc + hydrochloric acid releases H2 gas >>>Most chemical changes are not easily reversed, like many physical changes are.
21 Conservation of Mass – Key concept When you burn wood at a beach bonfire, the reaction produces carbon dioxide gas (CO2), water vapor (H2O) and some ash.It may seem that the amount of matter has been reduced when you look at the ash pile.However, if you could carefully measure the mass of the reactants and the mass of the products, you would find they are the same.This is the law of conservation of mass – mass is neither created or destroyed in a chemical reaction.
22 Conservation of MassLet’s say you have 32 grams of methane(CH4) that combine with 128 grams of oxygen gas to form 88 grams of carbon dioxide and an unknown number of grams of water.How much water is formed?𝐶 𝐻 4 +2 𝑂 𝐶 𝑂 2 + 𝐻 2 𝑂= x gramsSolve for xx = = 72 gThis is because mass of total reactants must equal mass of total products.