CHAPTER 7 AND PART 16 CHAPTER 7 AND PART 16

AP CHEMISTRYAP CHEMISTRY

LIGHTLIGHT

Wavelength = Wavelength = λλ– nm/ wave, m/wave, or nm or m nm/ wave, m/wave, or nm or m – λλf= c; c = 2.998 x 10f= c; c = 2.998 x 1088 m/s m/s Frequency = fFrequency = f– Waves/s or 1/s = c/ Waves/s or 1/s = c/ λλHigh frequency = short wavelengthHigh frequency = short wavelengthLow frequency = long wavelengthLow frequency = long wavelength

PHOTON ENERGYPHOTON ENERGYE = hfE = hfPlanck’s constant h = 6.626 x 10Planck’s constant h = 6.626 x 10-34-34 J J..ssContinuous spectrumContinuous spectrum– All wavelengthsAll wavelengthsLine spectrumLine spectrum– Discrete energies light going through a prismDiscrete energies light going through a prismROY G BIVROY G BIV

HYDROGEN ATOMHYDROGEN ATOMBohr model used hydrogen atomBohr model used hydrogen atomElectron orbits around nucleusElectron orbits around nucleusEnergy levels: Energy levels: Zero energy Zero energy – where a photon and electron are in where a photon and electron are in

completely separate energy states within an completely separate energy states within an atomatom

Ground state Ground state – lowest amount of energy an electron haslowest amount of energy an electron has

Excited state Excited state – electron getting extra energyelectron getting extra energy

E = hf = EE = hf = Ehihi - E - Elolo

Electrons can only give off certain energiesElectrons can only give off certain energies

QUANTUM NUMBERSQUANTUM NUMBERSMost probable place an electron can be foundMost probable place an electron can be foundΨΨ amplitude (height) of the electron wave amplitude (height) of the electron waveΨΨ 22 directly proportional to the probability of directly proportional to the probability of finding the electronfinding the electronQuantum numbersQuantum numbersPrincipal energy levelPrincipal energy level– n = 1, 2, 3, ..... etc.n = 1, 2, 3, ..... etc.SublevelsSublevels– s, p, d, and fs, p, d, and f– l = 0, 1, 2, 3, ...... etc.l = 0, 1, 2, 3, ...... etc.

CONTINUECONTINUEOrbitals or orientations– m = l to -l– l = 0 then m = 0– l = 1 then m = 1, 0, -1– l = 2 then m = 2, 1, 0, -

1, -2Spin– s = +1/2 , -1/2

Pauli Exclusion Principle– No two electrons can

have the same four quantum numbers

CapacitiesEach energy level (n) has n sublevelsEach sublevel (l) has 2l + 1 orbitalsEach orbital (m) has 2 electrons

CONTINUECONTINUEHeisenberg principleHeisenberg principle– state that there are limitations in knowing what state that there are limitations in knowing what

the position and momentum are at any given the position and momentum are at any given timetime

Probability distribution intensity of color -electron Probability distribution intensity of color -electron density mapdensity mapMost probable place to find a hydrogen electron Most probable place to find a hydrogen electron is .529Ǻ from nucleusis .529Ǻ from nucleus1Ǻ = 101Ǻ = 10-10 -10 mm

QUANTUM NUMBERSQUANTUM NUMBERS

Polyelectronic atomsPolyelectronic atoms– Treat electrons as if they have nuclear attraction and Treat electrons as if they have nuclear attraction and

average repulsion from other electronsaverage repulsion from other electrons– Effective nuclear chargeEffective nuclear charge– ZZeffeff = Z = Zactualactual - (electron repulsion) Z = atomic number - (electron repulsion) Z = atomic number

Periodic table can predict the filling of the sublevelsPeriodic table can predict the filling of the sublevels– Elements in groups Elements in groups – Elements in groups Elements in groups – Transition metals in groups Transition metals in groups – The two sets of 14 elements at the bottom of the table The two sets of 14 elements at the bottom of the table

fill fill

ORBITAL DIAGRAMORBITAL DIAGRAMHund’s rule Hund’s rule – Within a given sublevel, the order of filling is such Within a given sublevel, the order of filling is such

that there is the maximum number of half-filled that there is the maximum number of half-filled orbitalsorbitals

Monoatomic ion electron configurationMonoatomic ion electron configuration– Ions with noble gas configurationIons with noble gas configuration

Anions are formed from atoms with Anions are formed from atoms with Cations are formed from atoms with Cations are formed from atoms with

PERIODIC TRENDSPERIODIC TRENDSAtomic radiusAtomic radius

In general atomic radiiIn general atomic radii– Decreases as you move left to rightDecreases as you move left to right– Increases as you move downIncreases as you move down

Effective nuclear chargeEffective nuclear charge

– ZZeffectiveeffective = Z - S = Z - S

– Z = number or protonsZ = number or protons– S = number of core electrons that are shielding S = number of core electrons that are shielding

the outer electrons from the nucleusthe outer electrons from the nucleus

IONIC RADIUSIONIC RADIUSIonic radiusIonic radius– Ionic radius increases as you move down the Ionic radius increases as you move down the

groupgroup– Cations decrease left to rightCations decrease left to right– Anions decrease left to rightAnions decrease left to right

IONIZATION ENERGYIONIZATION ENERGYEnergy required to remove an electronEnergy required to remove an electronIncrease as you move across left to rightIncrease as you move across left to rightDecrease as you move downDecrease as you move down

ELECTRONEGATIVITYELECTRONEGATIVITYElectron AffinityElectron AffinityEnergy released from an atom as it acquires Energy released from an atom as it acquires another electronanother electronAtomic radiusAtomic radiusDecreases going across because the valence Decreases going across because the valence electrons are being pulled in, due to an electrons are being pulled in, due to an increase of proton attraction. Shielding increase of proton attraction. Shielding remains constant across the periodremains constant across the periodElectronegativityElectronegativityHow much an atom wants an electronHow much an atom wants an electron

METALSMETALSMetalsMetalsMetallic luster, ductile, malleable, good conductor Metallic luster, ductile, malleable, good conductor of heat and electricityof heat and electricityCompounds formed from metals and nonmetals Compounds formed from metals and nonmetals tend to be ionictend to be ionic

METALS AND NONMETALSMETALS AND NONMETALSNonmetalsNonmetals– No luster, poor conductors No luster, poor conductors – Nonmetals tend to gain electrons to become anionsNonmetals tend to gain electrons to become anions

When compounds are made up chiefly of nonmetals When compounds are made up chiefly of nonmetals they are molecular compoundsthey are molecular compoundsMost nonmetal oxides are Most nonmetal oxides are SemimetalsSemimetals– Some properties of both, brittle, semi-conductorSome properties of both, brittle, semi-conductor

Trends in metallic characteristics Trends in metallic characteristics – The more an element shows physical and chemical properties The more an element shows physical and chemical properties

characteristic for metals, increase right to left and top to characteristic for metals, increase right to left and top to bottom bottom