dr. s. m. condren chapter 7 quantum theory of the atom
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Dr. S. M. Condren
Chapter 7
Quantum Theory of the Atom
Dr. S. M. Condren
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.
Dr. S. M. Condren
Electromagnetic Radiation
Electromagnetic wave
• wavelength
• frequency
• amplitude
Dr. S. M. Condren
Electromagnetic Radiation
= c
where=> frequency
=> wavelength
c => speed of light
Dr. S. M. Condren
Wave Nature of the Electron
Dr. S. M. Condren
Electromagnetic Spectrum
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Line Emission Spectrum
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Line Spectrum
A spectrum produced by a luminous gas or vapor and appearing as distinct lines characteristic of the various elements constituting the gas.
Dr. S. M. Condren
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.
Dr. S. M. Condren
Ground State
The state of least possible energy in a physical system, as of elementary particles. Also called ground level.
Dr. S. M. Condren
Excited State
Being at an energy level higher than the ground state.
Dr. S. M. Condren
Photoelectric Effect
• the emission of electrons by substances, especially metals, when light falls on their surfaces.
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Photoelectric Effect
Dr. S. M. Condren
Quantum Mechanics
Quantum theory• the theory of the structure and behavior of
atoms and molecules.
Dr. S. M. Condren
Black Body Radiation
http://www.cbu.edu/~mcondren/C11599/BBvis.mov
Dr. S. M. Condren
Electromagnetic Radiation
Ehi - Elo = hc/where E => energy
h => Planck's constant
c => speed of light
=> wavelength
Dr. S. M. Condren
Photons
The quantum of electromagnetic energy, generally regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime.
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Dispersion of White Light
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The Atomic Spectrum of Hydrogen and the Bohr Model
Bohr Model for the Hydrogen Atom
mnr = nh/2p
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Bohr Atom
Dr. S. M. Condren
Bohr Model
E = -B/n2
where n => quantum number
1, 2, 3, 4, 5, 6, 7, etc
Dr. S. M. Condren
Bohr Model
for hydrogen
ground state: n = 1
excited state: n > 1
Dr. S. M. Condren
Bohr Model
E = (-2.179 X 10-18 J/part.)
(6.022 X 1023 part./mole)
(1 kJ/103 J)/n2
= (-1312 kJ/mol)(1/n2)
Dr. S. M. Condren
Electron Transition in a Hydrogen Atom
Lyman series => ultraviolet
n > 1 ==> n = 1
Balmer series => visible light
n > 2 ==> n = 2
Paschen series => infrared
n > 3 ==> n = 3
Dr. S. M. Condren
Line Spectra
See CHEMWORKS software
Dr. S. M. Condren
Absorption Spectrum
• Light shinning on a sample causes electrons to be excited from the ground state to an excited state
• wavelengths of that energy are removed from transmitted spectra
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Knowing diamond is transparent, which curve best represents the absorption spectrum of diamond (see below)?
A, B, C
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According to the energy diagram below for the Bohr model of the hydrogen atom, if an electron jumps from E1 to E2, energy is
absorbed
emitted
not involved
Dr. S. M. Condren
Heisenberg, Werner1901–76, German physicist
1932 Nobel Prize in physics
A founder of QUANTUM MECHANICS, he is famous for his uncertainty principle, which states that it is impossible to determine both the position and momentum of a subatomic particle (such as the electron) with arbitrarily high accuracy.
Dr. S. M. Condren
Heissenberg Uncertainty Principle
“it is impossible to determine both the position and momentum of a subatomic particle (such as the electron) with arbitrarily high accuracy”
The effect of this principle is to convert the laws of physics into statements about relative, instead of absolute, certainties.
Dr. S. M. Condren
Orbitals
• region of probability of finding an electron around the nucleus
• 5 types => s p d f
• maximum of 2 electrons per orbital
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Pure Atomic Orbitals
shape # of orbitals / energy level
s spherical 1
p dumbbell 3
d complex 5
f very complex 7
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Atomic Orbitals, s-type
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Atomic Orbitals, p-type
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Atomic Orbitals, d-type
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Atomic Orbitals, f-type
Dr. S. M. Condren
Shapes of Orbitals
http://www.colby.edu/chemistry/OChem/DEMOS/Orbitals.html
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