3. Waves and atomic spectrum of H Flashcards
Properties of waves
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Describe the electromagnetic spectrum
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What is interference?
Interference - the combination of two or more electromagnetic waveforms to form a wave in which displacement is reinforced or cancelled
In phase - waves up and down at the same point -> greater amplitude - constructive interferenc
Out of phase - highest and lowest points at the same time -> cancel out each other - destructive interference
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Which equation can be used to describe E of a photon?
E = hv
h - Planck’s constant
v (miu) - frequency of the light (in Hz/s)
Explain photoelectric effect
Photoelectric effect - a phenomenon where electrically charged particles are released from a material when it absorbs electromagnetic radiation
But the e has to have a certain amount of E to be ejected
E = hv = φ + EKE
φ - workfunction
EKE - kinetic E of ejected e
Requirement for photoelectric effect: hv ≥ φ + EKE
When ask for max wavelength that can eject an e from a material → min E required for photoelectric effect → EKE = 0 => λ = hc / φ
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Explain atomic (line) spectrum
H gives line spectrum - certain E needed to kick an e out in an atom (photoelectric effect)
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Bohr’s quantised model equation for E
n - principal quantum number (1, 2, 3, 4…) - only it changes because everything else (all conditions) is a constant -> E can only be certain numbers
pi - constant
me - mass of e
e - charge of e
h - Planck’s constant
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How do quantum numbers related to atomic orbitals?
The circular orbits represent the only possible energies that an electron can have
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Explain quantisation
Quantisation - subdivision into small but measurable increments
Quantisation of E - certain E needed to transition between different E levels
But the E levels are not equally spaced - as the the level increases, the E keep getting more similar
Explain the Rydberg equation
v (miu) - frequency
n - integer for energy levels
RH - the Rydberg constant 3.29 x 1015 Hz (H for hydrogen, their element - other constant)
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What are the different emission series?
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