Arrangement of electrons in atoms part 2 notes.notebook 1 October 20, 2015 Oct 185:17 PM 7"6%3 @ OQNFQDRRHUD QDOD@SHMF CHRSTQA@MBD SG@S ROQD@CR SGQNTFG @ LDCHTL EQNL @ ONHMS NE NQHFHM SN LNQD CHRS@MS ONHMSR Oct 185:18 PM %,%#42/-"'.%4)# 30%#425- Oct 188:51 PM Oct 185:20 PM 7GHSD KHFGS BNMS@HMR @KK BNKNQR @MC VGDM O@RRDC SGQNTFG @ OQHRL RGNVR @ #NMSHMTNTR RODBSQTL BNMSHMTNTR Q@MFD NE EQDPTDMBHDR Oct 188:54 PM Oct 188:55 PM
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Arrangement of electrons in atoms part 2 notes.notebook
1
October 20, 2015
Oct 185:17 PM
WAVES
a progressive, repeating disturbance that spreads through a medium from a point of origin to more distant points
Oct 185:18 PM
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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Oct 184:05 PM
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.
Oct 189:07 PM Oct 189:10 PM
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.
Oct 185:24 PM
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.
Oct 189:13 PM Oct 183:55 PM
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.
Oct 184:04 PM
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
Oct 184:07 PM
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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Oct 184:09 PM
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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Oct 184:12 PM
E2
E1
Ephoton = E2 E1 = hv
Oct 184:13 PM
Lyman: UV
Balmer: Visible
Paschen: IR
The electron of a hydrogen atom can exist only in very specific energy states.
Oct 184:14 PM
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
Oct 184:16 PM
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?
Oct 184:23 PM
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.
Oct 184:26 PM
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.
Oct 184:27 PM
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
Oct 184:37 PM
Heisenberg Uncertainty Principle: it is impossible to determine simultaneously both the position and velocity of an electron.