Unit 1

Unit 1Matter and MeasureChapters 1-32ChemistryWhat is Chemistry?Study of matter and the changes it undergoes

BranchesOrganicPhysicalAnalyticalBiochemicalInorganicUnit 4Periodic TableChapter 6Matter

Pure SubstancesElementsimplest form of matter that has a unique set of properties.Cant be broken down by chemical means

Compoundssubstance of two or more elements chemically combined in a fixed proportionCan be broken down by chemical means

MixturesPhysical blend of two or more substances

Two Types:HomogeneousComposition is uniform throughout

HeterogeneousComposition is not uniform throughout

Separating MixturesDifferences in physical properties can be used to separate mixturesFiltration Separates solids from liquids in heterogeneous mixturesDistillation Separates homogeneous liquid mixtures based on different boiling pointsEvaporation evaporate away liquid to leave solidChromatography separation of substances based on polarity and solubility

DensityAmount of matter in a given amount of space

Amount of mass in a given volume

Identifying SubstancesPhysical PropertyProperty of a substance that can be observed or measured without changing the substances compositionEx: Color, shape, size, mass

Physical Changesome properties change, but the composition remains the sameEx: melting, freezing, tearingIdentifying Substances (cont)Chemical Changechange that produces matter with a different composition than the original matterEx. burning, rusting, decomposing, exploding, corroding

Chemical propertyproperty that can only be observed by changing the composition of the substance.Ex: Reacting with, forming a new substance

Significant Figures (cont)If the decimal point is written, start on the LEFT side, go until you get to the first non-zero digit, count that one and every one from there to the end

1 2 30.00310 (3 sig. figs.)Significant Figures (cont)If the decimal point is not written, start on the RIGHT side, go until you get to the first non-zero digit, count that one and every one from there to the end

3 2 1 31,400

(3 sig. figs.)SigFigs for MathAddition and SubtractionAnswer has to have the same number of decimal places as least decimal places in what you are adding or subtracting

Multiplication and DivisionAnswer has to have same number of Sigfigs as least number of Sigfigs in what you are multiplying or dividing

Unit 2Atomic Theory and StructureChapters 4-515AtomAtoms are made of subatomic particlesProtonsNeutronsElectronsElectronDiscovered firstNegative charge (-1)Approx mass ~ 0uFound outside of nucleus

Valence ElectronElectrons in the outermost energy level

ProtonDiscovered secondPositive charge (+1)Approx mass ~ 1uFound inside nucleus

NeutronDiscovered lastNo charge (0)Approx mass ~ 1 atomic mass unit (u)Just slightly larger than a protonFound inside nucleus

Atomic StructureAtoms have no net charge# of electrons = # of protons

NucleusCenter of atom, contains protons and neutronsPositive charge

Atomic StructureAtomic NumberNumber of protonsAll atoms of the same element have the same number of protons

Mass NumberNumber of protons and neutrons in an atom# of Neutrons = Mass Number Atomic Number

Chemical SymbolsCl-35Chlorine-35

Mass NumberAtomic NumberAtomic StructureIsotopeatoms of the same element with different number of neutrons

IonAtom or group of atoms that have gained or lost one or more electronsHave a charge

Average Atomic MassAtomic MassWeighted average based on the relative abundance and mass number for all naturally occurring isotopes

Relative AbundancePercent of each naturally occurring isotope found in nature

Atomic MassC-1298.9%C-131.1%

Carbon = 0.989*12 + 0.011*13 = 12.011u

Atomic TheoriesDaltons Atomic ModelAlso called Hard Sphere ModelFirst model

Plum Pudding ModelUniform positive sphere with negatively charged electrons embedded within.Came as a result of discovery of electron

Rutherford Gold Foil Experiment Shot alpha particles at gold foilMost went through, some were deflected back

ConclusionsAtom is Mostly Empty SpaceDense positive core (nucleus)

Atomic TheoriesRutherford ModelDense positive core (nucleus)Electrons moving randomly around nucleus

Bohr ModelDense positive core (nucleus)Electrons in specified circular paths, called energy levels

Atomic TheoriesWave Mechanical ModelDense positive core (nucleus)Electrons in orbitalsRegions of space where there is a high probability of finding an electronModern (current) ModelAKA Quantum Mechanical Model, Electron Cloud ModelBohr ModelEach energy level can only hold up to a certain number of electrons

Level 1 2 electronsLevel 2 8 electronsLevel 3 18 electronsLevel 4 32 electronsElectron ConfigurationThe way in which electrons are arranged in the atom

Ground StateWhen the electrons are in the lowest available energy level (shown on reference tables)

Excited StateWhen one or more electrons are not in the lowest available energy levelValence ElectronsElectrons in the outermost energy level

Energy Level TransitionsElectrons can move between energy levels

Gaining energy will move an electron outward to a higher energy level

When an electron falls inward to a lower energy level, it releases a certain amount of energy as light

RadioisotopesNuclei of unstable isotopes are called radioisotopes.

An unstable nucleus releases energy by emitting radiation during the process of radioactive decayMass and/or energyRadiationLate 1800s discovery of radiation

Three TypesAlphaBetaGamma

RadiationThree Types

RadiationWhat it resemblesMassChargeStrengthAlphaHelium Nucleus4+2WeakestBetaElectron0-1MiddleGammaLight wave00StrongestSymbols

AlphaGammaBeta

Nuclear StabilityFor smaller atoms a ratio of 1:1 neutrons to protons helps to maintain stabilityC-12, N-14, O-16

For larger atoms, more neutrons than protons are required to maintain stabilityPb-207, Au-198, Ta-181

TransmutationsAny reaction where one element is transformed into a different elementNuclear Reactions

NaturalHas one reactantAlpha and Beta Decay

ArtificialHas more than one reactantParticle Accelerators

Radioactive DecayRadioisotopes will undergo decay reactions to become more stable

Alpha Decay

Beta Decay

Half LifeAmount of time for half of a sample to decay into a new element

Parent AtomsUndecayed atomsDaughter AtomsDecayed atomsHalf Life Equations

t = total amount of time elapsedT = half-lifeHalf Life Equationst = amount of time elapsedT = half-life

Half Life Equations

Mass LeftOriginal Mass=ExampleHow many half lives does it take for a sample of C-14 to be 11430 yrs old?

ExampleWhat fraction of P-32 is left after 42.84days?

ExampleHow long will a sample of Rn-222 take to decay down to 1/4 of the original sample?

7.646dPracticeHow much Carbon-14 was originally in a sample that contains 4g of C-14 and is 17145 years old?

32gMore PracticeHow much 226Ra will be left in a sample that is 4797 years old, if it initially contained 408g?

51gAnd One More.What is the half life of a sample that started with 144g and has only 9g left after 28days?

7dFissionSplitting of a larger atom into two or more smaller piecesNuclear Power Plants

One Example:

FusionJoining of two or more smaller pieces to make a larger pieceSun, StarsExamples

Energy ProductionEnergy is produced by a small amount of mass being converted to energyThis happens in both fission and fusionMore energy is produced by fusion than any other source

E=mc2

Fission vs. FusionAdvantages of FissionProduces a lot of energyCan be a controlled reactionMaterial is somewhat abundantFission vs. FusionDisadvantages of FissionUses hazardous materialProduces hazardous materialLong Half LifeReaction can run out of control.Limited amount of fissionable material

Fission vs. FusionAdvantages of FusionLighter weight materialEasily available materialProduces waste that is lighter and has shorter half-lifeProduces more energy than fission

Fission vs. FusionDisadvantages of FusionMust be done at very high temperaturesOnly been able to attain 3,000,000KHave not been able to sustain stable reaction for energy production

RadioisotopesYou must know these radioisotopes and usesI-131Diagnosing and treating thyroid disordersCo-60Treating cancerRadioisotopesYou must know these radioisotopes and usesC-14Dating living organismsCompare to C-12U-238Dating geologic formationsCompare to Pb-206

Dmitri Mendeleev1869 - Russian chemist and teacher, proposed a table for organizing elementsArranged the elements by increasing atomic mass.Left spaces for elements not yet discoveredPredicted very closely the properties of Ge, Ga, Sc, and 5 others

Periodic TableArranged in order of increasing atomic numberColumns are called GroupsNumbered 1-18Rows are called Periods

Periodic LawPeriodic Law When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.Group NamesGroup 1 - Alkali MetalsGroup 2 - Alkaline earth metalsGroup 17 HalogensGroup 18 - Inert or Noble gasesGroups 3-11 Transition MetalsBottom 2 rows Inner Transition

Valence ElectronsElectrons in outermost occupied energy level

Elements in the same group have similar properties because they have the same number of valence electronsPhases at STPMost elements are solids at STP

Hg and Br are liquids at STP

H, N, O, F, Cl and Noble Gases are all gases at STPClassifying ElementsElements are classified into 3 groups based on their properties:

Metals Left and Middle

Nonmetals Right

Metalloids - Staircase

MetalsGood conductors of heat and electrical currentHigh luster or sheenMany are ductile, meaning they can be drawn into wiresMost are malleable, meaning they can be hammered into thin sheetsNonmetalsMost are gases at room temperature, some are solids, and one is liquid

Most are poor conductors

Most solids are brittleMetalloidsB, Si, Ge, As, Sb, Te

Have properties of both metals and nonmetals, based on conditions

Exceptions:Al and Po are metalsAt is a nonmetal

Diatomic ElementsEight elements are diatomic molecules when alone in nature (exist as two atoms bonded together)H2, N2, O2, F2, Cl2, Br2, I2, At2Hydrogen and the Magic 7

IonsAtom, or group of atoms, that has gained or lost electrons

Cation positive ionAnion negative ion

IonsWhen an atom loses an electron, it becomes positively chargedThe radius becomes smallerMetals tend to lose electrons

When an atom gains an electron, it becomes negatively chargedThe radius becomes largerNonmetals tend to gain electrons

Properties (Table S)Atomic RadiusSize of the atom

Ionic RadiusSize of an ionProperties (Table S)First Ionization EnergyAmount of energy required to remove the outermost electron

ElectronegativityAbility of an atom to attract an electron from another atom when in a compound. Noble gases are omitted, dont form compounds

Periodic Table TrendsAtomic Number increases across a period.increases down a group

Atomic Mass generally increases across a period.increases down a group.

Periodic Table TrendsAtomic RadiusDecreases across a periodIncreases down a group

Ionic RadiusDecreases for positive/negative ions across a periodIncreases down a group

Periodic Table TrendsFirst Ionization EnergyTends to increase across a periodTends to decrease down a group

Electronegativity Tends to increase across a periodTends to decrease down a group

Metallic/Nonmetallic CharacterMetallic Character increases as you move towards the lower leftMost Metallic Element is Francium, Fr

Non-Metallic Character increases as you move towards upper rightMost nonmetallic element is Fluorine, F

80Trends SummaryPropertyPeriod (LR)Group (TB)Atomic NumberAtomic MassAtomic RadiusIonic RadiusIonization EnergyElectronegativity