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Transcript of Prentice-Hall © 2002General Chemistry: Chapter 9Slide 1 of 50 Philip Dutton University of Windsor,...
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 1 of 50
Philip DuttonUniversity of Windsor, Canada
Prentice-Hall © 2002
General ChemistryPrinciples and Modern Applications
Petrucci • Harwood • Herring
8th Edition
Chapter 9: Electrons in Atoms
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 2 of 50
Contents
9-1 Electromagnetic Radiation
9-2 Atomic Spectra
9-3 Quantum Theory
9-4 The Bohr Atom
9-5 Two Ideas Leading to a New Quantum Mechanics
9-6 Wave Mechanics
9-7 Quantum Numbers and Electron Orbitals
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 3 of 50
Contents
9-8 Quantum Numbers
9-9 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
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 4 of 50
9-1 Electromagnetic Radiation
• Electric and magnetic fields propagate as waves through empty space or through a medium.
• A wave transmits energy.
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 6 of 50
Frequency, Wavelength and Velocity
• Frequency () in Hertz—Hz or s-1.• Wavelength (λ) in meters—m.
• cm m nm pm
(10-2 m) (10-6 m) (10-9 m) (10-10 m) (10-12 m)
• Velocity (c)—2.997925 108 m s-1.
c = λ λ = c/ = c/λ
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 8 of 50
RedOrange
Yellow
Green
Blue
Indigo
Violet
Prentice-Hall ©2002 General Chemistry: Chapter 9 Slide 8
ROYGBIV
700 nm 450 nm
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 9 of 50
Constructive and Destructive Interference
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 14 of 50
9-3 Quantum Theory
Blackbody Radiation:
Max Planck, 1900:
Energy, like matter, is discontinuous.
є = h
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 15 of 50
The Photoelectric Effect
• Light striking the surface of certain metals causes ejection of electrons.
> o threshold frequency
• e- I• ek
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 17 of 50
The Photoelectric Effect
• At the stopping voltage the kinetic energy of the ejected electron has been converted to potential.
mu2 = eVs12
• At frequencies greater than o:
Vs = k ( - o)
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 18 of 50
The Photoelectric Effect
Eo = hoEk = eVs o = eVo
h
eVo, and therefore o, are characteristic of the metal.
Conservation of energy requires that:
h = mu2 + eVo2
1
mu2 = h - eVo eVs = 2
1
Ephoton = Ek + Ebinding
Ek = Ephoton - Ebinding
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 19 of 50
9-4 The Bohr Atom
E = -RH
n2
RH = 2.179 10-18 J
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 20 of 50
Energy-Level Diagram
ΔE = Ef – Ei = -RH
nf2
-RH
ni2
–
= RH ( ni2
1
nf2
–1
) = h = hc/λ
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 21 of 50
Ionization Energy of Hydrogen
ΔE = RH ( ni2
1
nf2
–1
) = h
As nf goes to infinity for hydrogen starting in the ground state:
h = RH ( ni2
1) = RH
This also works for hydrogen-like species such as He+ and Li2+.
h = -Z2 RH
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 22 of 50
Emission and Absorption Spectroscopy
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 23 of 50
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.
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 24 of 50
deBroglie and Matter Waves
E = mc2
h = mc2
h/c = mc = p
p = h/λ
λ = h/p = h/mu
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 26 of 50
The Uncertainty Principle
Δx Δp ≥ h
4π
• Werner Heisenberg
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 27 of 50
9-6 Wave Mechanics
2Ln
• Standing waves.– Nodes do not undergo displacement.
λ = , n = 1, 2, 3…
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 28 of 50
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.
L
xnsin
L
2ψ
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 30 of 50
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.
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 31 of 50
Principle Shells and Subshells
• Principle electronic shell, n = 1, 2, 3…• Angular momentum quantum number,
l = 0, 1, 2…(n-1)
l = 0, sl = 1, pl = 2, dl = 3, f
• Magnetic quantum number, ml= - l …-2, -1, 0, 1, 2…+l
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 33 of 50
9-8 Interpreting and Representing the Orbitals of the Hydrogen Atom.
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 38 of 50
9-9 Electron Spin: A Fourth Quantum Number
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 39 of 50
9-10 Multi-electron Atoms
• Schrödinger equation was for only one e-.
• Electron-electron repulsion in multi-electron atoms.
• Hydrogen-like orbitals (by approximation).
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 40 of 50
Penetration and Shielding
Zeff is the effective nuclear charge.
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 41 of 50
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.
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 47 of 50
Electon Configurations of Some Groups of Elements
Prentice-Hall © 2002 General Chemistry: Chapter 9 Slide 48 of 50
9-12 Electron Configurations and the Periodic Table