2 Describing Matter Matter Anything that takes up space and has mass A pure substance or as a matter of substancesProperties used to describe matter can be classified as extensive or intensiveExtensive PropertyDepends on the amount of matter in a sampleIntensive PropertyDepends on the type of matter in a sample (i.e. hardness)
3 Extensive Property Mass A measure of the amount of matter the object containsVolumeA measure of the space occupied by the object
4 States of MatterThree states of matter are: solid, liquid, and gas.
5 Solid Matter that has definite shape and volume Particles are tightly packed together (not easily compressed)
6 LiquidMatter that flows, has a fixed volume, and takes the shape of its containerParticles are packed less tightly than in a solid (not easily compressed)
7 Gas (Vapor) matter that has no definite shape or volume It takes the shape of its container and can be compressedParticles in a gas are spaced far apart (easily compressed)
8 Sample ExerciseWhat is the physical state of each of the following at room temperature?GoldGasolineHelium
9 Physical ChangesThe shape of a sample changes, but the composition stays the sameBoil, freeze, melt, condense, break, split, grind, cut, and crush.Physical changes can be reversible or irreversible
10 Section Assessment In what way are liquids and gases alike? In what way are liquids and solids different?Is the freezing of mercury (Hg) a reversible or irreversible physical change?
11 Classifying MixturesConsists of a physical blend of two or more substancesCan be classified as heterogeneous mixtures or as homogenous mixtures
12 Heterogeneous mixture not uniform in compositionEx: salad, stew
13 2. Homogeneous mixture A complete uniform composition Ex: iced tea, lemonadeAlso called a solution
14 Differences in physical properties can be used to separate mixtures DistillationA liquid is boiled to produce a vapor that is then condensed into a liquidThis process separates liquids by their boiling points (and impurities)Separating Mixtures
15 FiltrationSeparates a solid from the liquid in a heterogeneous mixture
16 DistillationA liquid is boiled to produce a vapor that is then condensed into a liquidThis process separates liquids by their boiling points (and impurities)
34 Distinguishing Substances and Mixtures Beryl - Be3Al2(SiO3)6Substance – if the composition of the material is fixed (elements, and compounds)Distinguishing Substances and Mixtures
35 MixtureIf the composition of a material may varyVarious Granite
36 Practice ProblemsLiquid A and Liquid B are clear liquids. They are placed in open containers and allowed to evaporate. When evaporation is complete, there is a white solid in container B, but no solid in container A. From these results, what can you infer about the two liquids?
37 Practice ProblemsA clear liquid in an open container is allowed to evaporate. After three days, a solid is left in the container. Was the clear liquid an element, a compound, or a mixture? How do you know?
38 Symbols and FormulasChemists use chemical symbols to represent elements, and chemical formulas to represent compounds.
39 Chemical Symbol Each element is represented by a one or two letters The first letter is always capitalizedWhen a second letter is used, it is lowercaseChemical formulas are used to represent compounds: CO2
40 Section Assessment Write the chemical symbol for each element Lead OxygenSilverSodiumHydrogenAluminum
41 Section assessmentName the chemical elements represented by the following symbolsCCaKAuFeCu
42 Chemical ChangeChange that produces matter with a different composition than the original matterUsually involves burning, rotting, decomposing, fermenting, exploding, rusting, corroding.Ex: milk spoils, electrolysis of water
44 Chemical Reactions Chemical Property The ability of a substance to undergo a specific chemical changeDuring a chemical change, the composition of matter always changesA substance that is present at the start of the reaction is a reactantA substance produced in the reaction is a product
45 Recognizing Chemical Changes Possible clues to a chemical change include:A transfer of energyA change in colorThe production of a gasThe formation of a precipitatePrecipitate (ppt)A solid that forms and settles out of a liquid mixture, and is usually indicated by a color change
51 Section AssessmentClassify the following changes as physical or chemical changesWater boilsSalt dissolves in waterMilk turns sourA metal rusts
52 Section AssessmentHydrogen and oxygen react chemically to form water. How much water would form if 4.8 grams of hydrogen reacted with 38.4 grams of oxygen?2H2 + O2 2H2O
53 Section AssessmentWhen ammonium nitrate (NH4NO3) explodes, the products are nitrogen, oxygen, and water. When 40 grams if ammonia nitrate explode 14 grams of nitrogen and 8 grams of oxygen form. How many grams of water form?NH4NO3 N2 + O2 + H2O
54 Key Concepts - Properties of Matter Properties used to describe matter can be classified as extensive or intensiveEvery sample of a given substance has identical intensive properties because every sample has the same compositionThree states of matter are solid, liquid, and gasPhysical changes can be classified as reversible or irreversible
55 Key Concepts - Mixtures Mixtures can be classified as heterogeneous mixtures or as homogeneous mixtures, based on the distribution of their componentsDifference in physical properties can be used to separate mixtures
56 Key Concepts – Elements and Compounds Compounds can be broken down into simpler substances by chemical means, but elements cannotIf the composition of a material is fixed, the material is a substance. If the composition may vary, the material is a mixtureChemists use chemical symbols to represent elements, and chemical formulas to represent compoundsKey Concepts – Elements and Compounds
57 Key Concepts – Chemical Reactions During a chemical change, the composition of matter always changesFour possible clues to chemical change include a transfer of energy, a change in color, the production of a gas, or the formation of a precipitateDuring any chemical reaction, the mass of the products is always equal to the mass of the reactants