4 Properties Words that describe matter (adjectives) Physical Property - a property that can be observed and measured without changing the substance.Examples:Chemical Property - a property that can only be observed by changing the type of substance.
5 Properties Words that describe matter (adjectives) Extensive Property - depend on the amount of matterEx:Intensive Property - only depend on the type of matter, not the amountUsed to identify a substance
6 States of matterSolid- matter that can not flow and has definite volume.Liquid- definite volume but takes the shape of its container (flows).Gas- a substance without definite volume or shape and can flow.Vapor- a substance that is currently a gas but normally is a liquid or solid at room temperature.
7 States of Matter Definite Volume? Definite Shape? Com-pressible? Solid Expansion w/ Temp. increaseCom-pressible?Small Expans.SolidYESYESNOSmall Expans.LiquidNONOYESLarge Expans.GasNONOYES
9 States of Matter Plasma: Occurs at high temperature low pressure Formed when electrons separate from nucleus of gasesMost common state of matter in the universe
10 Physical Changes & Chemical Changes Changes in MatterPhysical Changes & Chemical Changes
11 Physical ChangesThese alter the appearance of matter without changing its composition.Examples?Changes of the state (or phase) of matter is a physical changeThe temperature & pressure at which matter changes phase are important physical propertiesThese are melting & boiling points
12 Another Way to Change States PressureFor some substances it will turn solids to liquidsEX: Ice SkatingFor others it will turn liquids to solidsEx: Silly PuttyWill turn gas to liquidCompressor in refrigerator and ACWill turn gas to solidFormation of Dry Ice
13 Chemical ChangesOccur when one or more substances react and form a new substanceThese are also called chemical reactionsProducts of the chemical reactions ALWAYS have different properties than the original materials
14 Evidence of Chemical Reactions: Formation of a gasFormation of a solidprecipitateDrastic color changeEnergy changes – temp. changes or formation of lightExothermic vs. Endothermic ReactionsChange in the smell of a substance
15 Conservation of MassMass can not be created or destroyed in ordinary chemical changesAll the mass can be accounted forMass at the start = mass at endSo the total mass of the products should equal the total mass of the reactants
16 Antoine Lavoisier Considered the father of modern Chemistry Discovered the Law of Conservation of Mass (also called the Law of Conservation of Matter)Did experiments on reactions.
17 Mixtures A physical combination of two or more substances Heterogeneous - you can see the individual substances that make it up.Ex: Chocolate chip cookie dough, gravel, soil.Homogeneous- you cannot see the individual substances that make it up, it always has a single phase.Ex: Kool-aid, air.
18 Solutions Another name for homogeneous mixture Can occur between any state of matter.Examples:LiquidSolidGas
19 Separating mixtures Only physical changes - no new matter formed Filtration- separate solids from liquids with a barrierDistillation- separate because of different boiling pointsHeat mixtureCatch purified vapor in cooled area
20 Chromatography- different substances are attracted to paper or gel, so move at different speeds Crystallization – pure solids form when solid particles come out of solution (make crystals)
22 Elements Simplest pure substance Cannot be broken down into simpler matter by normal physical or chemical meansAll one kind of atomEach one has a unique name and symbol. In the symbol the first letter is always capitalized and the remaining letter(s) are lowercase.There are 91 naturally occurring elementsWho was given credit for organizing them into a table?Dmitri Mendeleev
23 Compounds Chemical combinations of two or more different elements When they are broken down, the pieces have completely different properties than the compound.For example: SaltMost of the substances we work with are compounds
24 Chemical Symbols Used to write chemical formulas You know it is a formula because there will be more than one capital letterSubscripts tell us how many of each atom in the formula.H2OC3H8HBrO3
25 Laws of CompoundsBy accounting for the mass of all matter there are a couple of laws that govern how compounds are created.Law of Definite ProportionsLaw of Multiple Proportions
26 Law of Definite Proportions Each compound has a specific ratio of elements by massIt is always a whole # ratioFor example – the chemical formula for water is always H2OYou can also see its ratio by mass:Water is always 8 grams of oxygen for each gram of hydrogenThis does not change, no matter where you are on Earth! (Or in the universe for that matter)
27 Law of Def. Prop. Continued… This law can be verified by determining the percent by mass of the elements in a compound:Example: A compound contains g of iron and g of oxygen. What is the percent composition of oxygen?30.05 % Oxygen
28 Law of Multiple Proportions The textbook states that when the same elements combine to make different compounds, they combine in small whole number ratios.You will NOT get fractions of elementsExamples:CuCl vs. CuCl2CH4 vs. C2H6
29 ReviewWhat makes a form of matter a substance? What are some examples?How do you distinguish between chemical and physical properties?What is the difference between a physical change and a chemical change? Give one example of each.Why is a solution a homogeneous mixture? What is one way to separate a homogeneous mixture?Explain how you would tell that NaCl is a compound but Na is an element.Explain how all compounds obey the laws of definite and multiple proportions.