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Published byCarissa Avey Modified over 3 years ago

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Aim: How can we explain energy transitions in an atom? Do Now: What were the limitations of the Rutherford model of the atom and how did the Bohr model explain these limitations?

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Emission Spectra When electron falls from higher to lower level, photon is emitted. Shows as bright series of lines.

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Visible spectrum

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Balmer Series Named after Johann Jacob Balmer 1825-1898

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Gas Tube Demo

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Energy of final level Energy of initial level Energy of photon emitted or absorbed

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Calculate the energy of the photon emitted when a hydrogen atom changes from energy state n = 3 to n= 2, in eV and Joules E photon = E i – E f E photon = -1.51 eV – (-3.40 eV) E photon = 1.89 eV 1.89 eV * 1.60 x 10 -19 J = 3.0x10 -19 J 1 eV

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For a mercury electron transition from level c to a, calculate E photon, λ, f, and the type of EM wave emitted. E photon = E i – E f E photon = -5.52 eV – (-10.38 eV) E photon = 4.86 eV 4.86 eV * 1.60 x 10 -19 J = 7.77 x 10 -19 J 1 eV

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c= fλ 3.00 x 10 8 m/s = f (2.56 x 10 -7 m) f = 1.17 x 10 15 Hz This is ultraviolet light E photon = hc λ 7.77 x 10 -19 J = (6.63x10 -34 Js)(3 x 10 8 m/s) λ λ = 2.56 x 10 -7 m

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An electron in a hydrogen atom drops from n = 4, n = 2. Find E photon (eV and Joules), f, and the color of light. E photon = E i – E f E photon = -0.85 eV – (-3.40 eV) E photon = 2.55 eV 2.55 eV * 1.60 x 10 -19 J = 4.08 x 10 -19 J 1 eV

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E photon = hf 4.08 x 10 -19 J = (6.63 x 10 -34 Js)f f = 6.15 x 10 14 Hz This is blue light

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Calculate the energy of the photon needed when a hydrogen atom changes from n =1 to n =∞ E photon = E i – E f E photon = -13.60 eV – 0.00 eV E photon = -13.60 eV

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Ionization Potential Minimum energy needed to remove an electron from the ground state to infinity For hydrogen -13.6 eV For mercury -10.38 eV

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A positive photon energy indicated photon is emitted A negative photon energy indicates photon is absorbed

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Absorption Spectra When electron jumps to a higher energy level a photon is absorbed. Shows up as a series of dark lines.

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Wave Model After De Broglie proposed matter waves, he was able to show the Bohr model could be explained by considering the orbits of a series of waves

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Cloud Model (Shrödinger’s Model) Quantum mechanics indicates the probability of the electron being in a certain area Most probable regions are in area called ‘electron cloud’ Energy levels of Bohr model are divided into sublevels and orbitals -- together with Cloud model define the current model Erwin Shrödinger 1887-1961

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