2MatterDef: anything that takes up space and has mass
3States of Matter Liquid Solid Flows (takes the shape of its container) Has definite shape and volumeParticles are tightly packed and locked in place (incompressible)Not defined by rigidity or hardnessLiquidFlows (takes the shape of its container)Indefinite shapeConstant/Definite volumeExpands when heatedVirtually incompressibleTakes the shape of the containerParticles are less closely packed; can move past each other
4States of Matter cont. Gas Flows Takes the shape AND volume of the container (Indefinite shape and volume)Particles are spaced far apart and easily compressedVaporSubstance in the gaseous state that is a solid or a liquid at room temperatureExample: steam
6SubstancesDef: Matter that has a uniform and unchanging composition (pure substance)ExamplesTable Salt: always sodium and chlorideWater: always hydrogen and oxygenNOT sea water…why not?
7Pure SubstancesDef: matter that has a uniform and unchanging compositionTwo types:ElementsCannot be separated into simpler substancesContain all the same atomsEx: C, Al, Cu, Hg, Au
8Elements 92 naturally occurring on Earth Unique name and symbol Dmitri Mendeleev organized 1st periodic tablePeriods = horizontal rowsGroups or families = vertical rows
9Pure Substances cont. Compounds Combination of 2 or more elements Can be broken down into elements by a chemical reactionEx: H2O, NaCl, CO2, etc.Properties of elements are different than when they form compoundsMolecules – smallest particle of a compound or element
11MixturesDef: a combination of two or more pure substances in which each pure substance retains its individual chemical propertiesTwo Types of Mixtures:HeterogenousHomogenous
12Heterogeneous Mixture Mixture that is not completely uniformIndividual substances remain distinct
13Homogeneous Mixture Mixture that is uniform throughout Particles are evenly mingledaka Solutions –Def: homogeneous mixture of 2 or more substancesContain very small particlesSolvent – dissolving agent (usually a liquid)Solute – substance being dissolved (usually a solid)Aqueous solution – any solution whose solvent is waterExamples:Salt and waterAir – mixture of gasesAlloys
14Homogeneous Mixture - Alloy Def: A homogenous mixture of metals, or a mixture of one metal and one nonmetal, in which the metal substance is the major componentUsed by manufactures to achieve greater strength and durabilityUsed in spacecrafts and automobiles
15Techniques Used for Separation FiltrationSeparates a liquid from a solid (heterogeneous mixtures)DistillationPhysically separates most homogeneous mixtures based on boiling point differences of the substancesCrystallizationProduces pure solid particles of a substance from a solution that contains the dissolved substanceChromatographySeparates components of a mixture on its ability to travel or be drawn across the surface of another material
17Joseph Proust (France 1799) Law of Definite Proportions:A given compound always contains elements in a certain proportion by mass. (Constant composition).
18Law of Definite Proportions Atoms combine in whole number ratios, so their proportion by mass will always be the same.Example: H2O is always made up of 2 atoms of H and one atom of O.The ratio of O to H in water is always ( : ) which is 16:2 or 8:1.
19Example Law of Definite Proportions : KCl always contains one atom of K for every one atom of ClIn KCl, potassium and chlorine always have a ratio of ( to ) or ~1:1 by mass.
20Law of Definite Proportions Formula:Percent by mass (%) = mass of element x 100mass of compound
21ExampleA compound of sucrose is made up of the elements carbon, hydrogen, and oxygen. Carbon makes up 8.44 grams, hydrogen makes up 1.30 grams, and oxygen makes up grams. Find the percent by mass of each of the elements in the compound.
22Law of Definite Proportions Percent by mass (%) = mass of element x 100mass of compoundLaw of Definite ProportionsColumn 1Column 2ElementAnalysis by mass (g)Percent by mass (%)Carbon8.44 g carbon8.44 g Carbon x 10020.00 g Sucrose = 42.20% CarbonHydrogen1.30 g hydrogen1.30 g Hydrogen x 10020.00 g Sucrose = 6.50% HydrogenOxygen10.26 g oxygen10.26 g Oxygen x 10020.00 g Sucrose = 51.30% OxygenTotal20.00 g sucrose= 100%
23Law of Multiple Proportions (John Dalton) When the same two elements combine to form more than one compound:the ratios of the mass of one element in the first compound to its mass in the second compound, (as it combines with the same mass of the other element), can always be expressed as ratios of small whole numbers( ex: 1:3 or 2:5).ExampleWater (H2O) = 2:1 Hydrogen to OxygenPeroxide (H2O2) = 2:2 Hydrogen to Oxygen
24Example of Law of Multiple Proportions Carbon combines with oxygen to form CO and CO2 .Mass of Carbon(g)Mass of Oxygen(g)Ratio of O in CO2 to O in COCO12.0116.00CO232.002:1
25ExampleIn the carbon compounds ethane (C2H6) and ethene (C2H4), what is the lowest whole number ratio of H atoms that react with the same number of C atoms?Answer: 3:2
26Physical ChangesDef: Change that alters at least one of the physical properties of the substanceDoes not change the chemical compositionExamples:Changing the physical state – i.e. freezing, melting, etc.DissolvingAltering the shape or size
27Physical propertiesDef: Observed or measured without changing the chemical composition or identity of the substanceIntensiveDoesn’t depend on the amount of the substanceAlways remain the same for a given substanceEx: melting point, boiling point, densityExtensiveDepends on how much matter is being consideredEx: mass, volume, sizeAlso, properties that can change for a substanceEx: color, state, shape
28Chemical changesDef: a change in the chemical composition of a substance (cannot go back to original form)Occurs as a chemical reactionExamples:Iron rusting to form iron (III) oxideFermentation of grape juice
29Chemical propertiesDef: the ability of a substance to undergo chemical reactions and to form new substancesExamples:Rusting is a chemical property of ironAbility to rot, rust, decompose, ferment, corrode, grow, and decayPhysical changes indicate a chemical change has occurredEx: heat, light, flame, gas bubbles, changes in color, formation of a solid, etc.
30Law of Conservation of Mass Def: States that mass is neither created nor destroyed during a chemical reaction; it is CONSERVEDMass reactants = Mass productsH O2 H2Oreactants productsTotal mass started is the same at the end