Quantum Model of the Atom l Bohr l de Broglie l Heisenberg l Schrödinger.
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Transcript of Quantum Model of the Atom l Bohr l de Broglie l Heisenberg l Schrödinger.
Quantum Model of the AtomQuantum Model of the Atom
BohrBohr de Brogliede Broglie Heisenberg Heisenberg SchrödingerSchrödinger
Neils Bohr (1885 –1962)Neils Bohr (1885 –1962)
Bohr Model Bohr Model of the of the
Hydrogen Hydrogen AtomAtom
Bohr model of the atomBohr model of the atom
In the Bohr In the Bohr model, model,
electrons electrons can only can only exist at exist at specific specific
energy levels energy levels (orbit).(orbit).
Energy
Line SpectraLine Spectra
Line spectrum of Hydrogen is Line spectrum of Hydrogen is produced when an electron produced when an electron drops from a higher-energy drops from a higher-energy orbit to a lower energy orbit.orbit to a lower energy orbit.
Specifically, Specifically,
EEphotonphoton = E = E2 2 - E- E11 = h = h
Bohr Checked it with Math.Bohr Checked it with Math.
Used mass and charge of the Used mass and charge of the electron together with Planck’s electron together with Planck’s constant and calculated where constant and calculated where the spectral lines should be and the spectral lines should be and they were!they were!
Problem -- only worked for Problem -- only worked for Hydrogen!Hydrogen!
Bohr model of the atomBohr model of the atom The Bohr model is a The Bohr model is a
‘planetary’ type ‘planetary’ type model.model.
Each principal Each principal quantum represents quantum represents a new ‘orbit’ or layer.a new ‘orbit’ or layer.
The nucleus is at the The nucleus is at the center of the model.center of the model.
Hydrogen Spectrum (cont.)Hydrogen Spectrum (cont.)
Each line of the Hydrogen Each line of the Hydrogen spectrum is produced by spectrum is produced by and corresponds to the and corresponds to the
emission of photons with emission of photons with specific energies (E = hspecific energies (E = h))
Hold It!Hold It! Nay, Nay says “Classical” Nay, Nay says “Classical”
theory.theory. Hydrogen should be excited by Hydrogen should be excited by
whatever amount of energy.whatever amount of energy. Should be continuous spectrumShould be continuous spectrum What’s with the lines????What’s with the lines????
Why wouldn’t there be an Why wouldn’t there be an infinite number of energy levels infinite number of energy levels for electrons?for electrons?
Photoelectric effect and Photoelectric effect and Hydrogen spectrum.Hydrogen spectrum.
Neils Bohr (1885 –1962)Neils Bohr (1885 –1962)
Bohr Model Bohr Model of the of the
Hydrogen Hydrogen AtomAtom
Louis de Broglie Louis de Broglie (1892-1987)(1892-1987)
Electrons should Electrons should be considered be considered
waves confined waves confined to the space to the space around an around an
atomic nucleusatomic nucleus
The Quantum Atom (cont.)The Quantum Atom (cont.)
Since electrons are waves, Since electrons are waves, they can amplify and cancel they can amplify and cancel out when in and out of sync.out when in and out of sync.
Therefore only certain Therefore only certain energies of electrons are energies of electrons are possible.possible.
Werner HeisenbergWerner Heisenberg
Heisenberg Heisenberg Uncertainty Uncertainty
Principle – It is Principle – It is impossible to impossible to determine the determine the position and position and velocity of an velocity of an
electron electron simultaneously.simultaneously.
Heisenberg uncertainty Heisenberg uncertainty principleprinciple
In order to observe an electron, In order to observe an electron, one would need to hit it with one would need to hit it with photons having a very short photons having a very short wavelength.wavelength.
Short wavelength photons Short wavelength photons would have a high frequency would have a high frequency and a great deal of energy.and a great deal of energy.
Heisenberg uncertainty Heisenberg uncertainty principleprinciple
If one were to hit an electron, it If one were to hit an electron, it would cause the motion and the would cause the motion and the speed of the electron to change.speed of the electron to change.
Lower energy photons would Lower energy photons would have a smaller effect but would have a smaller effect but would not give precise information.not give precise information.
Heisenberg Uncertainty Heisenberg Uncertainty PrinciplePrinciple
Holt Online LearningHolt Online Learning
Erwin Schrödinger Erwin Schrödinger (1887-1961)(1887-1961)
Schrödinger Schrödinger developed the developed the
calculus to calculus to describe the describe the
wavewave behavior behavior and energies of and energies of
electrons in electrons in atoms.atoms.
Bohr vs. Schrödinger Bohr vs. Schrödinger Orbits vs. OrbitalsOrbits vs. Orbitals
Bohr -- definite Bohr -- definite distinct distinct orbitsorbits populated by populated by
electron electron particles.particles.
Bohr vs. Schrödinger Bohr vs. Schrödinger Orbits vs. OrbitalsOrbits vs. Orbitals
Schrödinger -- electron are Schrödinger -- electron are waves (de Broglie) with a waves (de Broglie) with a
certain probability certain probability (mathematical model) of (mathematical model) of
being found in three being found in three dimensional regions around dimensional regions around
the nucleus - orbitalsthe nucleus - orbitals