Download Chapter 1: Matter and Measurement

General Chemistry
Principles and Modern Applications
Petrucci • Harwood • Herring
8th Edition
Chapter 9: Electrons in Atoms
Philip Dutton
University of Windsor, Canada
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General Chemistry: Chapter 9
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Contents
9-1
9-2
9-3
9-4
9-5
9-6
9-7
Electromagnetic Radiation
Atomic Spectra
Quantum Theory
The Bohr Atom
Two Ideas Leading to a New Quantum Mechanics
Wave Mechanics
Quantum Numbers and Electron Orbitals
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General Chemistry: Chapter 9
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Contents
9-8
9-9
Quantum Numbers
Interpreting and Representing Orbitals of the
Hydrogen Atom
9-9 Electron Spin
9-10 Multi-electron Atoms
9-11 Electron Configurations
9-12 Electron Configurations and the Periodic Table
Focus on Helium-Neon Lasers
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General Chemistry: Chapter 9
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9-1 Electromagnetic Radiation
• Electric and magnetic fields
propagate as waves through
empty space or through a
medium.
• A wave transmits energy.
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General Chemistry: Chapter 9
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EM Radiation
Low 
High 
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General Chemistry: Chapter 9
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Frequency, Wavelength and Velocity
• Frequency () in Hertz—Hz or s-1.
• Wavelength (λ) in meters—m.
• cm
m
nm

(10-2 m)
(10-6 m) (10-9 m)
pm
(10-10 m) (10-12 m)
• Velocity (c)—2.997925  108 m s-1.
c = λ
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λ = c/
General Chemistry: Chapter 9
= c/λ
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Electromagnetic Spectrum
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General Chemistry: Chapter 9
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ROYGBIV
Red
Orange
Yellow
700 nm
450 nm
Green
Blue
Indigo
Violet
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General
GeneralChemistry:
Chemistry: Chapter
Chapter99
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Constructive and Destructive Interference
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General Chemistry: Chapter 9
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General Chemistry: Chapter 9
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Refraction of Light
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General Chemistry: Chapter 9
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9-2 Atomic Spectra
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Atomic Spectra
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9-3 Quantum Theory
Blackbody Radiation:
Max Planck, 1900:
Energy, like matter, is discontinuous.
є = h
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The Photoelectric Effect
• Light striking the surface of certain metals
causes ejection of electrons.
•  > o
• e-  I
• ek  
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threshold frequency
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The Photoelectric Effect
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General Chemistry: Chapter 9
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The Photoelectric Effect
• At the stopping voltage the kinetic energy of the
ejected electron has been converted to potential.
1
mu2 = eVs
2
• At frequencies greater than o:
Vs = k ( - o)
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General Chemistry: Chapter 9
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The Photoelectric Effect
Ek = eVs
Eo = ho
eVo
o =
h
eVo, and therefore o, are characteristic of the metal.
Conservation of energy requires that:
Ephoton = Ek + Ebinding
Ek = Ephoton - Ebinding
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1
mu2 + eVo
h =
2
1
eVs =
mu2 = h - eVo
2
General Chemistry: Chapter 9
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9-4 The Bohr Atom
-RH
E= 2
n
RH = 2.179  10-18 J
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General Chemistry: Chapter 9
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Energy-Level Diagram
-RH -RH
– 2
ΔE = Ef – Ei =
2
nf
ni
1
1
–
= RH ( 2
) = h = hc/λ
2
ni
nf
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General Chemistry: Chapter 9
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Ionization Energy of Hydrogen
1
1
–
ΔE = RH ( 2
) = h
2
ni
nf
As nf goes to infinity for hydrogen starting in the ground state:
1
h = RH ( 2 ) = RH
ni
This also works for hydrogen-like species such as He+ and Li2+.
h = -Z2 RH
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Emission and Absorption Spectroscopy
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General Chemistry: Chapter 9
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9-5 Two Ideas Leading to a New Quantum
Mechanics
• Wave-Particle Duality.
– Einstein suggested particle-like properties of
light could explain the photoelectric effect.
– But diffraction patterns suggest photons are
wave-like.
• deBroglie, 1924
– Small particles of matter may at times display
wavelike properties.
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deBroglie and Matter Waves
E = mc2
h = mc2
h/c = mc = p
p = h/λ
λ = h/p = h/mu
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General Chemistry: Chapter 9
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X-Ray Diffraction
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General Chemistry: Chapter 9
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The Uncertainty Principle
• Werner Heisenberg
h
Δx Δp ≥
4π
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General Chemistry: Chapter 9
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9-6 Wave Mechanics
• Standing waves.
– Nodes do not undergo displacement.
2L
λ=
, n = 1, 2, 3…
n
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Wave Functions
• ψ, psi, the wave function.
– Should correspond to a
standing wave within the
boundary of the system being
described.
• Particle in a box.
ψ 
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General Chemistry: Chapter 9
2
 n x 
sin 

L
 L 
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Probability of Finding an Electron
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General Chemistry: Chapter 9
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Wave Functions for Hydrogen
• Schrödinger, 1927
Eψ = H ψ
– H (x,y,z) or H (r,θ,φ)
ψ(r,θ,φ) = R(r) Y(θ,φ)
R(r) is the radial wave function.
Y(θ,φ) is the angular wave function.
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Principle Shells and Subshells
• Principle electronic shell, n = 1, 2, 3…
• Angular momentum quantum number,
l = 0, 1, 2…(n-1)
l = 0, s
l = 1, p
l = 2, d
l = 3, f
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• Magnetic quantum number,
ml= - l …-2, -1, 0, 1, 2…+l
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Orbital Energies
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General Chemistry: Chapter 9
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9-8 Interpreting and Representing the
Orbitals of the Hydrogen Atom.
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s orbitals
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p Orbitals
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p Orbitals
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d Orbitals
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General Chemistry: Chapter 9
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9-9 Electron Spin: A Fourth Quantum
Number
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General Chemistry: Chapter 9
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9-10 Multi-electron Atoms
• Schrödinger equation was for only one e-.
• Electron-electron repulsion in multielectron atoms.
• Hydrogen-like orbitals (by approximation).
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General Chemistry: Chapter 9
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Penetration and Shielding
Zeff is the effective nuclear charge.
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9-11 Electron Configurations
• Aufbau process.
– Build up and minimize energy.
• Pauli exclusion principle.
– No two electrons can have all four quantum
numbers alike.
• Hund’s rule.
– Degenerate orbitals are occupied singly first.
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General Chemistry: Chapter 9
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Orbital Energies
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General Chemistry: Chapter 9
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Orbital Filling
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Aufbau Process and Hunds Rule
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Filling p Orbitals
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Filling the d Orbitals
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General Chemistry: Chapter 9
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Electon Configurations of Some Groups of
Elements
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9-12 Electron Configurations and the Periodic Table
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Focus on He-Ne Lasers
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General Chemistry: Chapter 9
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Chapter 9 Questions
1, 2, 3, 4, 12, 15,
17, 19, 22, 25, 34,
35, 41, 67, 69, 71,
83, 85, 93, 98
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General Chemistry: Chapter 9
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