Arrangement of electrons in atoms part 2 notes.notebook
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WAVES
a progressive, repeating disturbance that spreads through a medium from a point of origin to more distant points
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ELECTROMAGNETIC SPECTRUM
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White light contains all colors and when passed through a prism, shows a
Continuous spectrum: continuous range of frequencies
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Arrangement of electrons in atoms part 2 notes.notebook
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Things that waves do:
constructive and destuctive interference
diffraction
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Diffraction
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analysis of light emitted when an element is strongly heated or energized by electricity
EMISSON SPECTROSCOPY
An emission spectrum is unique for each element. Like an atomic fingerprint.
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All solids emit some electromagnetic radiation at all temperatures...mostly IR.
Arrangement of electrons in atoms part 2 notes.notebook
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When heating objects to high temperatures, solids emit radiation we can see:
Black body radiation: depends on the temperature of a solid and NOT on the particular elements present.
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Max Planck studied black body radiation and found a single relationship between the energy and frequency of emitted radiation.
He introduced a NEW fundamental
constant (h) and proposed that vibrating
atoms in a heated solid could absorb and
emit energy only in certain discrete amounts...the smallest amount = QUANTUM.
Won a Nobel Prize in 1918.
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The Photoelectric EffectWhen shining a light on a piece of metal, electrons are kicked out of the metal.
Wave Theory:
Said that light of any frequency should dislodge the electrons bc waves have constructional interference
Big Time Discrepancy:
If the light's frequency is too low, no matter how long the light is shone, no electrons are kicked out.
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Albert Einstein* expanded on Planck's theory and introduced the concept that electromagnetic radiation has a DUAL WAVEPARTICLE nature.
(1905)
** each particle of light carries a quantum of energy
PHOTON: particle of electromagnetic radiation having zero mass and carries a quantum of energy
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Matter only absorbs energy in whole numbers of photons
To kick electrons off of a piece of metal, the photons have to have a minimum frequency, or minimum energy, to make this work
Different metals have different binding energies.
Arrangement of electrons in atoms part 2 notes.notebook
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Ground state: lowest energy state of an atom.
Excited state: a state where an atom has higher potential energy that its ground state
Line emission spectrum: bands of light emitted when electrons fall from excited states to lower energy states.
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E2
E1
Ephoton = E2 E1 = hv
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Lyman: UV
Balmer: Visible
Paschen: IR
The electron of a hydrogen atom can exist only in very specific energy states.
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BOHR MODEL(Niels Bohr 1913)
* proposed a theory that linked the atom's electron with photon emission.
* The electron is only allowed in specific "orbits" around nucleus.
* Orbits have definite, fixed energy.
Lowest energy state = ground state
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Ladder and potential energy:
Arrangement of electrons in atoms part 2 notes.notebook
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Where Bohr's theory failed:
1. Couldn't not explain atoms with more than one electron.
2. Could not explain the chemical behavior of atoms.
* was using classical physics to explain atomic behavior
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THE QUANTUM MODEL OF THE ATOMThe investigations into the photoelectric effect and hydrogen atomic emission revealed that light could behave as both a wave and a particle.
COULD ELECTRONS DO THE SAME?
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Louis de Broglie* pointed out that the electron's of Bohr's quantized orbits behaved a lot like waves.
Guitar strings: any wave confined to a space can have only certain frequencies
Electron waves could exist only at specific frequencies.
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Electrons can be bent (diffraction)
Electron beams can show interference (when waves overlap) reduction of energy in some areas and an increase in energy in other areas.
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HEISENBERG UNCERTAINTY PRINCIPLE(1927)
* if electrons are both waves and particles, then where are they in the atom?Heisenberg's idea involved detecting electrons by their interaction with photons.
* Because photons have the about the same energy as electrons, the photons knock the electron off its path.
* Always an uncertainty when trying to locate an electron.
https://www.youtube.com/watch?v=TQKELOE9eY4
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Heisenberg Uncertainty Principle: it is impossible to determine simultaneously both the position and velocity of an electron.
Arrangement of electrons in atoms part 2 notes.notebook
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SCHRODINGER WAVE EQUATION(1926)
Used the hyposthesis that electrons have a diual waveparticle nature and developed an equation that treated electrons in atoms as waves.
Only waves of specific energies (frequencies) provided solutions to the equation.
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QUANTUM THEORYDescribes mathematically the wave properties of electrons and other very small particles.
Solutions to Schrodinger's wave equation are known as wave functions.
Wave functions give only the probability of finding the electron.
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Electrons do NOT travel in orbits.
Electrons exist in certain regions called orbitals. a 3D region around the nucleus that indictes the probable location of an electron.
Electrons in orbitals have quantized energies.
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