1. Chapter 8: Electrons in Atoms
Chemistry 140 Fall 2002
CHEMISTRY
Ninth
Edition
GENERAL
Principles and Modern Applications
Petrucci • Harwood • Herring • Madura
Chapter 8: Electrons in Atoms
Iron rusts
Natural gas burns
Represent chemical reactions by chemical equations.
Relationship between reactants and products is STOICHIOMETRY
Many reactions occur in solution-concentration uses the mole concept to describe solutions
Dr. Mendenhall
Lecture 2
April 14, 2010
General Chemistry: Chapter 8
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2. General Chemistry: Chapter 8
Objectives
1 Electromagnetic Radiation
Quantum Numbers and Electron Orbitals
Know how orbital energies are modified when more than one electron is present in an atom
General Chemistry: Chapter 8
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3. 8-1 Electromagnetic Radiation
Electric and magnetic fields propagate as waves through empty space or through a medium.
A wave transmits energy.
General Chemistry: Chapter 8
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4. General Chemistry: Chapter 8
EM Radiation
Low 
High 
General Chemistry: Chapter 8
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5. 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)—  108 m s-1.
c = λ λ = c/ = c/λ
General Chemistry: Chapter 8
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6. Electromagnetic Spectrum
General Chemistry: Chapter 8
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7. General Chemistry: Chapter 8
Refraction of Light
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General Chemistry: Chapter 8
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8. General Chemistry: Chapter 8
Chemistry 140 Fall 2002
9-2 Atomic Spectra
(a) (b) (c) (d) (e)
Hydrogen
Helium
Lithium
Sodium
Potassium
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General Chemistry: Chapter 8
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9. General Chemistry: Chapter 8
Atomic Spectra
Helium
Hydrogen
General Chemistry: Chapter 8
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10. General Chemistry: Chapter 8
Chemistry 140 Fall 2002
8-3 Quantum Theory
Blackbody Radiation:
Heated bodies emit light
Blackbody Radiation
I  λ
Classical theory predicts continuous increase of intensity with wavelength.
1900, Max Planck made the revolutionary proposal that ENERGY, LIKE MATTER, IS DISCONTINUOUS.
Introduces the concept of QUANTA of energy.
h = x J s.
Max Planck, 1900
є = h
Energy, like matter, is discontinuous.
General Chemistry: Chapter 8
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11. The Photoelectric Effect
Heinrich Hertz, 1888
Light striking the surface of certain metals causes ejection of electrons.
 > o
threshold frequency
#e-  I
ek  
Albert Einstein 1905
General Chemistry: Chapter 8
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12. The Photoelectric Effect
Chemistry 140 Fall 2002
The Photoelectric Effect
Phonton strikes a bound eletron which absorbges the energy, if binding energy (known as the work function) is less than photon energy, the e- is ejected.
Stopping voltage of photoelectrons as a function of frequency of incident radiation.
Threshold frequency found by extrapolation.
General Chemistry: Chapter 8
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13. 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)
General Chemistry: Chapter 8
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14. The Photoelectric Effect
eVo
Ek = eVs
Eo = ho
o = h
eVo, and therefore o, are characteristic of the metal.
Conservation of energy requires that: 1
Ephoton = Ek + Ebinding
h =
mu2 + eVo 2 1
Ek = Ephoton - Ebinding
eVs =
mu2 = h - eVo 2
General Chemistry: Chapter 8
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15. 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
Magnetic quantum number, ml= - l …-2, -1, 0, 1, 2…+l
General Chemistry: Chapter 8
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16. General Chemistry: Chapter 8
Orbital Energies
General Chemistry: Chapter 8
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17. Relationship b/w quantum numbers & atomic orbitals
General Chemistry: Chapter 8
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18. General Chemistry: Chapter 8
Orbital Energies
Degenerate orbitals: orbitals that have same energy
General Chemistry: Chapter 8
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19. General Chemistry: Chapter 8
Orbital Filling
General Chemistry: Chapter 8
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20. 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.
General Chemistry: Chapter 8
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21. Aufbau Process and Hunds Rule
General Chemistry: Chapter 8
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22. General Chemistry: Chapter 8
Filling p Orbitals
General Chemistry: Chapter 8
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23. General Chemistry: Chapter 8
Filling the d Orbitals
General Chemistry: Chapter 8
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24. General Chemistry: Chapter 8
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25. 8-12 Electron Configurations and the Periodic Table
General Chemistry: Chapter 8
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