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Chapter 7Chapter 7
Quantum Theory of the Atom
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Electromagnetic RadiationElectromagnetic Radiation
Electromagnetic waveA 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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Electromagnetic RadiationElectromagnetic Radiation
Electromagnetic wavewavelengthfrequency amplitude
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Electromagnetic RadiationElectromagnetic Radiation
= c
where=> frequency
=> wavelength
c => speed of light
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Wave Nature of the ElectronWave Nature of the Electron
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Electromagnetic SpectrumElectromagnetic Spectrum
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Line Emission SpectrumLine Emission Spectrum
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Line SpectrumLine Spectrum
A spectrum produced by a luminous gas or vapor and appearing as distinct lines characteristic of the various elements constituting the gas.
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Emission SpectrumEmission 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.
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Ground StateGround State
The state of least possible energy in a physical system, as of elementary particles. Also called ground level.
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Excited StateExcited State
Being at an energy level higher than the ground state.
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Photoelectric EffectPhotoelectric Effect
the emission of electrons by substances, especially metals, when light falls on their surfaces.
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Photoelectric EffectPhotoelectric Effect
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Quantum MechanicsQuantum Mechanics
Quantum theorythe theory of the structure and behavior of
atoms and molecules.
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Black Body RadiationBlack Body Radiation
http://www.cbu.edu/~mcondren/C11599/BBvis.mov
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Electromagnetic RadiationElectromagnetic Radiation
Ehi - Elo = hc/where E => energy
h => Planck's constant
c => speed of light
=> wavelength
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PhotonsPhotons
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 LightDispersion of White Light
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The Atomic Spectrum of The Atomic Spectrum of HydrogenHydrogen
and the Bohr Model and the Bohr ModelBohr Model for the Hydrogen Atom
mnr = nh/2p
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Bohr AtomBohr Atom
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Bohr ModelBohr Model
E = -B/n2
where n => quantum number
1, 2, 3, 4, 5, 6, 7, etc
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Bohr ModelBohr Model
for hydrogen
ground state: n = 1
excited state: n > 1
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Bohr ModelBohr 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)
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Electron Transition in a Hydrogen Electron Transition in a Hydrogen AtomAtom
Lyman series => ultraviolet
n > 1 ==> n = 1
Balmer series => visible light
n > 2 ==> n = 2
Paschen series => infrared
n > 3 ==> n = 3
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Line SpectraLine Spectra
See CHEMWORKS software
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Absorption SpectrumAbsorption 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
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Heisenberg, WernerHeisenberg, Werner1901–76, German physicist1901–76, German physicist
1932 Nobel Prize in physics1932 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.
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Heissenberg Uncertainty Heissenberg Uncertainty PrinciplePrinciple
“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.
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OrbitalsOrbitals
region of probability of finding an electron around the nucleus
4 types => s p d fmaximum of 2 electrons per orbital
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Pure Atomic OrbitalsPure 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-Atomic Orbitals, s-typetype
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Atomic Orbitals, p-Atomic Orbitals, p-typetype
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Atomic Orbitals, d-typeAtomic Orbitals, d-type
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Atomic Orbitals, f-typeAtomic Orbitals, f-type
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Shapes of OrbitalsShapes of Orbitals
http://www.colby.edu/chemistry/OChem/DEMOS/Orbitals.html