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I. Waves & Particles Ch. 4 - Electrons in Atoms
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A. Waves zWavelength ( ) - length of one complete wave zFrequency ( ) - # of waves that pass a point during a certain time period yhertz (Hz) = 1/s zAmplitude (A) - distance from the origin to the trough or crest
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A. Waves A greater amplitude (intensity) greater frequency (color) crest origin trough A
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B. EM Spectrum LOWENERGYLOWENERGY HIGHENERGYHIGHENERGY
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LOWENERGYLOWENERGY HIGHENERGYHIGHENERGY ROYG.BIV redorangeyellowgreenblueindigoviolet
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B. EM Spectrum zFrequency & wavelength are inversely proportional c = c:speed of light (3.00 10 8 m/s) :wavelength (m, nm, etc.) :frequency (Hz)
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B. EM Spectrum GIVEN: = ? = 434 nm = 4.34 10 -7 m c = 3.00 10 8 m/s WORK : = c = 3.00 10 8 m/s 4.34 10 -7 m = 6.91 10 14 Hz zEX: Find the frequency of a photon with a wavelength of 434 nm.
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C. Quantum Theory zPlanck (1900) yObserved - emission of light from hot objects yConcluded - energy is emitted in small, specific amounts (quanta) yQuantum - minimum amount of energy change
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C. Quantum Theory zPlanck (1900) vs. Classical TheoryQuantum Theory
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C. Quantum Theory zEinstein (1905) yObserved - photoelectric effect
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C. Quantum Theory zEinstein (1905) yConcluded - light has properties of both waves and particles “wave-particle duality” yPhoton - particle of light that carries a quantum of energy
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C. Quantum Theory E:energy (J, joules) h:Planck’s constant (6.6262 10 -34 J·s) :frequency (Hz) E = h zThe energy of a photon is proportional to its frequency.
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C. Quantum Theory GIVEN: E = ? = 4.57 10 14 Hz h = 6.6262 10 -34 J·s WORK : E = h E = ( 6.6262 10 -34 J·s ) ( 4.57 10 14 Hz ) E = 3.03 10 -19 J zEX: Find the energy of a red photon with a frequency of 4.57 10 14 Hz.
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II. Bohr Model of the Atom Ch. 4 - Electrons in Atoms
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A. Line-Emission Spectrum ground state excited state ENERGY IN PHOTON OUT
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B. Bohr Model ze - exist only in orbits with specific amounts of energy called energy levels zTherefore… ye - can only gain or lose certain amounts of energy yonly certain photons are produced
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B. Bohr Model 1 2 3 4 5 6 zEnergy of photon depends on the difference in energy levels zBohr’s calculated energies matched the IR, visible, and UV lines for the H atom
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C. Other Elements zEach element has a unique bright-line emission spectrum. y“Atomic Fingerprint” Helium zBohr’s calculations only worked for hydrogen!
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III. Quantum Model of the Atom Ch. 4 - Electrons in Atoms
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A. Electrons as Waves zLouis de Broglie (1924) yApplied wave-particle theory to e - ye - exhibit wave properties QUANTIZED WAVELENGTHS
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A. Electrons as Waves QUANTIZED WAVELENGTHS
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A. Electrons as Waves EVIDENCE: DIFFRACTION PATTERNS ELECTRONS VISIBLE LIGHT
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B. Quantum Mechanics zHeisenberg Uncertainty Principle yImpossible to know both the velocity and position of an electron at the same time
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B. Quantum Mechanics zSchrödinger Wave Equation (1926) yfinite # of solutions quantized energy levels ydefines probability of finding an e -
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B. Quantum Mechanics Radial Distribution Curve Orbital zOrbital (“electron cloud”) yRegion in space where there is 90% probability of finding an e -
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C. Quantum Numbers UPPER LEVEL zFour Quantum Numbers: ySpecify the “address” of each electron in an atom
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C. Quantum Numbers 1. Principal Quantum Number ( n ) yEnergy level ySize of the orbital yn 2 = # of orbitals in the energy level
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C. Quantum Numbers s p d f 2. Angular Momentum Quantum # ( l ) yEnergy sublevel yShape of the orbital
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C. Quantum Numbers zn=# of sublevels per level zn 2 =# of orbitals per level zSublevel sets: 1 s, 3 p, 5 d, 7 f
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C. Quantum Numbers 3. Magnetic Quantum Number ( m l ) yOrientation of orbital Specifies the exact orbital within each sublevel
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C. Quantum Numbers pxpx pypy pzpz
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zOrbitals combine to form a spherical shape. 2s 2p z 2p y 2p x
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C. Quantum Numbers 4. Spin Quantum Number ( m s ) yElectron spin +½ or -½ yAn orbital can hold 2 electrons that spin in opposite directions.
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C. Quantum Numbers 1. Principal # 2. Ang. Mom. # 3. Magnetic # 4. Spin # energy level sublevel (s,p,d,f) orbital electron zPauli Exclusion Principle yNo two electrons in an atom can have the same 4 quantum numbers. yEach e - has a unique “address”:
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Feeling overwhelmed? Read Section 4-2!
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IV. Electron Configuration (p. 105 - 116, 128 - 139) Ch. 4 - Electrons in Atoms
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A. General Rules zPauli Exclusion Principle yEach orbital can hold TWO electrons with opposite spins.
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A. General Rules zAufbau Principle yElectrons fill the lowest energy orbitals first. y“Lazy Tenant Rule”
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RIGHT WRONG A. General Rules zHund’s Rule yWithin a sublevel, place one e - per orbital before pairing them. y“Empty Bus Seat Rule”
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O 8e - zOrbital Diagram zElectron Configuration 1s 2 2s 2 2p 4 B. Notation 1s 2s 2p
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zShorthand Configuration S 16e - Valence Electrons Core Electrons S16e - [Ne] 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 4 B. Notation zLonghand Configuration
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© 1998 by Harcourt Brace & Company s p d (n-1) f (n-2) 12345671234567 6767 C. Periodic Patterns
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zPeriod # yenergy level (subtract for d & f) zA/B Group # ytotal # of valence e - zColumn within sublevel block y# of e - in sublevel
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s-block1st Period 1s 1 1st column of s-block C. Periodic Patterns zExample - Hydrogen
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C. Periodic Patterns zShorthand Configuration yCore e - : Go up one row and over to the Noble Gas. yValence e - : On the next row, fill in the # of e - in each sublevel.
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[Ar]4s 2 3d 10 4p 2 C. Periodic Patterns zExample - Germanium
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zFull energy level zFull sublevel (s, p, d, f) zHalf-full sublevel D. Stability
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zElectron Configuration Exceptions yCopper EXPECT :[Ar] 4s 2 3d 9 ACTUALLY :[Ar] 4s 1 3d 10 yCopper gains stability with a full d-sublevel. D. Stability
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zElectron Configuration Exceptions yChromium EXPECT :[Ar] 4s 2 3d 4 ACTUALLY :[Ar] 4s 1 3d 5 yChromium gains stability with a half-full d-sublevel. D. Stability
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zIon Formation yAtoms gain or lose electrons to become more stable. yIsoelectronic with the Noble Gases.
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O 2- 10e - [He] 2s 2 2p 6 D. Stability zIon Electron Configuration yWrite the e - config for the closest Noble Gas yEX: Oxygen ion O 2- Ne
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Ch. 5 - The Periodic Table I. History
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A. Mendeleev zDmitri Mendeleev (1869, Russian) yOrganized elements by increasing atomic mass. yElements with similar properties were grouped together. yThere were some discrepancies.
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A. Mendeleev zDmitri Mendeleev (1869, Russian) yPredicted properties of undiscovered elements.
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B. Moseley zHenry Mosely (1913, British) yOrganized elements by increasing atomic number. yResolved discrepancies in Mendeleev’s arrangement.
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II. Organization of the Elements Ch. 5 - The Periodic Table
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zMetals zNonmetals zMetalloids A. Metallic Character
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zMain Group Elements zTransition Metals zInner Transition Metals B. Blocks
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III. Periodic Trends Ch. 5 - The Periodic Table
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A. Periodic Law zWhen elements are arranged in order of increasing atomic #, elements with similar properties appear at regular intervals.
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B. Chemical Reactivity zFamilies ySimilar valence e - within a group result in similar chemical properties
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B. Chemical Reactivity zAlkali Metals zAlkaline Earth Metals zTransition Metals zHalogens zNoble Gases
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zAtomic Radius ysize of atom © 1998 LOGAL zFirst Ionization Energy yEnergy required to remove one e - from a neutral atom. © 1998 LOGAL zMelting/Boiling Point C. Other Properties
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zAtomic Radius D. Atomic Radius Li Ar Ne K Na
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zAtomic Radius yIncreases to the LEFT and DOWN D. Atomic Radius
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zWhy larger going down? yHigher energy levels have larger orbitals yShielding - core e - block the attraction between the nucleus and the valence e - zWhy smaller to the right? yIncreased nuclear charge without additional shielding pulls e - in tighter D. Atomic Radius
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zFirst Ionization Energy E. Ionization Energy K Na Li Ar Ne He
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zFirst Ionization Energy yIncreases UP and to the RIGHT E. Ionization Energy
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zWhy opposite of atomic radius? yIn small atoms, e - are close to the nucleus where the attraction is stronger zWhy small jumps within each group? yStable e - configurations don’t want to lose e - E. Ionization Energy
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zSuccessive Ionization Energies yMg1st I.E.736 kJ 2nd I.E.1,445 kJ Core e - 3rd I.E.7,730 kJ yLarge jump in I.E. occurs when a CORE e - is removed. E. Ionization Energy
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yAl1st I.E.577 kJ 2nd I.E.1,815 kJ 3rd I.E.2,740 kJ Core e - 4th I.E.11,600 kJ zSuccessive Ionization Energies yLarge jump in I.E. occurs when a CORE e - is removed. E. Ionization Energy
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zMelting/Boiling Point yHighest in the middle of a period. F. Melting/Boiling Point
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zIonic Radius yCations (+) xlose e - xsmaller © 2002 Prentice-Hall, Inc. yAnions (–) xgain e - xlarger G. Ionic Radius
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zWhich atom has the larger radius? yBeorBa yCaorBr Ba Ca Examples
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zWhich atom has the higher 1st I.E.? yNorBi yBaorNe N Ne Examples
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zWhich atom has the higher melting/boiling point? yLiorC yCrorKr C Cr Examples
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zWhich particle has the larger radius? ySorS 2- yAlorAl 3+ S 2- Al Examples
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Periodic Trends Summary
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