1. Chapter 7
Atomic Structure
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2. ELECTROMAGNETIC RADIATION
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3. Electromagnetic Spectrum
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4. Electromagnetic Radiation
Electromagnetic wave
A wave of energy having a frequency within the electromagnetic spectrum and propagated as a periodic disturbance of the electromagnetic field when an electric charge oscillates or accelerates.
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5. Electromagnetic Radiation
Electromagnetic wave
wavelength
frequency
amplitude
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6. Electromagnetic Radiation
Figure 7.1
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7. Wave motion: wave length and nodes
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8. Wave Nature of the Electron
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9. Electromagnetic Radiation
Waves have a frequency
Use the Greek letter “nu”, , for frequency, and units are “cycles per sec”
Use the Greek letter “lambda”, l, for wavelength, and units are “meters”
All radiation:  •  = c
c = velocity of light = 3.00 x 108 m/sec
Long wavelength --> small frequency
Short wavelength --> high frequency
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10. Electromagnetic Radiation
Long wavelength --> small frequency
Short wavelength --> high frequency
increasing frequency
increasing wavelength
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11. Fireworks
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12. Flame Tests
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13. The Electric Pickle Excited atoms can emit light.
Here the solution in a pickle is excited electrically. The Na+ ions in the pickle juice give off light characteristic of that element.
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14. Line Emission Spectrum
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15. Electromagnetic Radiation
Example: Calculate the frequency, n, of red light that has a wavelength, l, of 700. nm.
= (1/700. nm)(109nm/1m)(3.00x108m/sec)
= 4.29x1014 s-1
= 4.29x1014 cycles/s
= 4.29x1014 hertz
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16. Electromagnetic Radiation
Short wavelength -->
high frequency
high energy
Long wavelength -->
small frequency
low energy
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17. Black Body Radiation http://www.cbu.edu/~mcondren/C11599/BBvis.mov
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18. Experiment demonstrates the particle nature of light.
Photoelectric Effect
Experiment demonstrates the particle nature of light.
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19. Energy of Radiation Energy of 1.00 mol of photons of red light.
E = h•
= (6.63 x J•s)(4.29 x 1014 s-1)
= x J per photon
E per mol =
(2.85 x J/ph)(6.02 x 1023 ph/mol)
= kJ/mol
This is in the range of energies that can break bonds.
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20. Spectra
Line Spectrum
A spectrum produced by a luminous gas or vapor and appearing as distinct lines characteristic of the various elements constituting the gas.
Emission Spectrum
The spectrum of bright lines, bands, or continuous radiation characteristic of and determined by a specific emitting substance subjected to a specific kind of excitation.
Absorption Spectrum
Wavelengths of light that are removed from transmitted light.
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21. Atomic Line Emission Spectra
and Niels Bohr
Bohr’s greatest contribution to science was in building a simple model of the atom. It was based on an understanding of the SHARP LINE EMISSION SPECTRA of excited atoms.
Niels Bohr
( )
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22. Energy of state = - C/n2 Atomic Spectra and Bohr
Bohr said classical view is wrong.
e- can only exist in certain discrete orbits — called stationary states.
e- is restricted to QUANTIZED energy states.
Energy of state = - C/n2
where n = quantum no. = 1, 2, 3, 4, ....
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23. Bohr Atom
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24. Energy States Ground State
The state of least possible energy in a physical system, as of elementary particles. Also called ground level.
Excited States
Being at an energy level higher than the ground state.
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25. Energy Adsorption/Emission
Active Figure 7.11
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26. Atomic Spectra and Bohr
C has been found from experiment (and is now called R, the Rydberg constant)
R (= C) = kJ/mol or 3.29 x 1015 cycles/sec
so, E of emitted light
= (3/4)R = x 1015 sec-1
and l = c/n = nm
This is exactly in agreement with experiment!
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27. Line Emission Spectra of Excited Atoms
High E
Short 
High 
Low E
Long 
Low 
Visible lines in H atom spectrum are called the BALMER series.
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28. Origin of Line Spectra Balmer series Active Figure 7.12
Paschen series
Balmer series
Active Figure 7.12
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29. Atomic Line Spectra and Niels Bohr
Bohr’s theory was a great accomplishment.
Rec’d Nobel Prize, 1922
Problems with theory —
theory only successful for H.
introduced quantum idea artificially.
So, we go on to QUANTUM or WAVE MECHANICS
Niels Bohr
( )
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30. Quantum or Wave Mechanics
Schrodinger applied idea of e- behaving as a wave to the problem of electrons in atoms.
He developed the WAVE EQUATION
Solution gives set of math expressions called WAVE FUNCTIONS, 
Each describes an allowed energy state of an e-
Quantization introduced naturally.
E. Schrodinger
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31. WAVE FUNCTIONS, 
•is a function of distance and two angles.
• Each  corresponds to an ORBITAL — the region of space within which an electron is found.
•  does NOT describe the exact location of the electron.
• 2 is proportional to the probability of finding an e- at a given point.
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32. Uncertainty Principle
Problem of defining nature of electrons solved by W. Heisenberg.
Cannot simultaneously define the position and momentum (=m*v) of an electron.
We define e- energy exactly but accept limitation that we do not know exact position.
W. Heisenberg
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33. Types of Orbitals
s orbital
p orbital
d orbital
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34. Orbitals s orbitals p orbitals d orbitals f orbitals
No more than 2 e- assigned to an orbital
Orbitals grouped in s, p, d (and f) subshells
s orbitals
also
p orbitals
d orbitals
f orbitals
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35. 1 3 5 7 2 6 10 14 s orbitals p orbitals d orbitals f orbitals
No.
orbs. 1 3 5 7
No. e- 2 6 10 14
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36. n (principal) => shell l (angular) => subshell
QUANTUM NUMBERS
The shape, size, and energy of each orbital is a function of 3 quantum numbers:
n (principal) => shell
l (angular) => subshell
ml (magnetic) => designates an orbital within a subshell
s (spin) => designates the direction of spin
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37. Symbol Values Description
QUANTUM NUMBERS
Symbol Values Description
n (principal) 1, 2, 3, .. Orbital size and energy where E = -R(1/n2)
l (angular) 0, 1, 2, .. n-1 Orbital shape or type (subshell)
ml (magnetic) -l..0..+l Orbital orientation
# of orbitals in
subshell = 2 l + 1
s (spin) -1/2 or +1/2 Direction of spin of electron
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38. Types of Atomic Orbitals
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39. Atomic Orbitals
Types of orbitals found in the known elements: s, p, d, and f
schools play defensive football
Packer version: secondary pass defense fails
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40. S Orbitals 1s 2s 3s
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41. p Orbitals The three p orbitals lie 90o apart in space
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42. 3px Orbital
2px Orbital
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43. d Orbitals 3dxy Orbital 3dxz Orbital 3dyz Orbital 3dx2- y2 Orbital
3dz2 Orbital
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