lecture #3, atomic structure ( rutherford , bohr models) - mit
TRANSCRIPT
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Periodic Table Quiz
Name Grade /10
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La Loony Ce chemistryPr professorNd needsPm partner:Sm seekingEu educatedGd graduateTb toDy developHo hazardousEr experimentsTm testingYb youngLu lab assistants.
cannot be referring to 3.091!
must be the “other” chemistry professor
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CEase not I to slave, back breaking to tend;PRideless and bootless stoking hearth and fire.No Dream of mine own precious time to spendPour'ed More to sate your glutt'nous desire.SMelting anew my ten-thousandth hourEUtopia forever I eschew.Growing Dimmer is my fleeing powerTo Bid these curs'ed problem sets adieu.DYing away whilst thy hosts are foughtHOpeless I come should in lecture I doze.ERgo, like a sad slave, stay and rest nought.Then Must I tool and toil while fatigue grows. Yet, Bloody though I must be, and quite ill Light the Universal abyss I will.
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Lanthanum
57
La3*
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The Structure of the Atomstatus report ca. end of the 19th century
* atom is electrically neutral
* -ve charge carried by electrons
* e- has very small mass
bulk of the atom is +ve,
most mass resides in +ve charge
Question: what is the spatial distribution of charge inside an atom?
b
Marsden's Analysis
Scattering of an α-particle which approaches a heavy nucleus with an impact parameter b.
θTrajectory of incident α particle
gold nucleus
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principles of modern chemistry:
* recognize patterns
* develop a quantitative model that - explains our observations - makes predictions that can be tested by experiment
Bohr Postulates for the Hydrogen Atom 1. Rutherford atom is correct 2. Classical EM theory not applicable to orbiting e-
3. Newtonian mechanics applicable to orbiting e-
4. Eelectron = Ekinetic + Epotential
5. e- energy quantized through its angular momentum: L = mvr = nh/2π, n = 1, 2, 3,…
6. Planck-Einstein relation applies to e- transitions: ΔE = Ef - Ei = hν = hc/λ
c = νλ
Bohr Postulates for the Hydrogen Atom 1. Rutherford atom is correct 2. Classical EM theory not applicable to orbiting e-
3. Newtonian mechanics applicable to orbiting e-
4. Eelectron = Ekinetic + Epotential
5. e- energy quantized through its angular momentum: L = mvr = nh/2π, n = 1, 2, 3,…
6. Planck-Einstein relation applies to e- transitions: ΔE = Ef - Ei = hν = hc/λ
c = νλ
Bohr Postulates for the Hydrogen Atom 1. Rutherford atom is correct 2. Classical EM theory not applicable to orbiting e-
3. Newtonian mechanics applicable to orbiting e-
4. Eelectron = Ekinetic + Epotential
5. e- energy quantized through its angular momentum: L = mvr = nh/2π, n = 1, 2, 3,…
6. Planck-Einstein relation applies to e- transitions: ΔE = Ef - Ei = hν = hc/λ
c = νλ
Bohr Postulates for the Hydrogen Atom 1. Rutherford atom is correct 2. Classical EM theory not applicable to orbiting e-
3. Newtonian mechanics applicable to orbiting e-
4. Eelectron = Ekinetic + Epotential
5. e- energy quantized through its angular momentum: L = mvr = nh/2π, n = 1, 2, 3,…
6. Planck-Einstein relation applies to e- transitions: ΔE = Ef - Ei = hν = hc/λ
c = νλ
0 500 1000 1500 2000 2500 3000
5000 K
4000 K
3000 K
Rad
iatio
n in
tens
ity
Wavelength (nm)
Classical prediction6000 K
E = hν
Planck suggests that light is composed of energypackets or quanta. The elementary unit of e-mradiation is the photon.
InfraredVisibleUV
6000 K
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Bohr Postulates for the Hydrogen Atom 1. Rutherford atom is correct 2. Classical EM theory not applicable to orbiting e-
3. Newtonian mechanics applicable to orbiting e-
4. Eelectron = Ekinetic + Epotential
5. e- energy quantized through its angular momentum: L = mvr = nh/2π, n = 1, 2, 3,…
6. Planck-Einstein relation applies to e- transitions: ΔE = Ef - Ei = hν = hc/λ
c = νλ
© source unknown. All rights reserved. This image is excluded from our Creative Commonslicense.For more information,
see http://ocw.mit.edu/fairuse.
© source unknown. All rightsreserved. This image isexcluded from our CreativeCommons license. For moreinformation, seehttp://ocw.mit.edu/fairuse.
© source unknown. All rights reserved. This image is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.
© source unknown. All rights reserved. This image is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.
© source unknown. All rights reserved. This image is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.
Isotopes of Hydrogen
hydrogen1766 Henry Cavendish, London
deuterium
1931 Harold Urey, Columbia U. tritium
1934 Ernest Rutherford, Cambridge U.
Dalton proposes theindivisible unit of an element is the atom.
1803
Thomson discovers electrons,believed to reside within a sphere of uniform positive
charge (the "plum pudding" model).
1904
Rutherford demonstrates the existence of a positively chargednucleus that contains nearly all
the mass of an atom.
1911
Bohr proposes fixed circularorbits around the nucleus
for electrons.
1913
In the current model of theatom, electrons occupy regions of space (orbitals) around the
nucleus determined by their energies.
1926
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J. J. Thomson (1856-1940)Cathode ray = Charged particle = Electron (1897)charge-to-mass ratio of electron (1897)
J.J Thomson"Plum pudding" model of atom (1904)
Robert Millikan (1868-1953) Charge and mass of electron (1909)
James Chadwick (1891-1974)Neutron (1932)
Ernest RutherfordProton (1920)
Ernest RutherfordNuclear model of atom (1911)
Ernest Rutherford (1871-1937)α and β particles (1898)
Marie and Pierre Curie(1867-1934, 1854-1906)Radioactive elements polonium and radium (1898)
Henri Becquerel (1852-1908)Uranium emits rays that fog photographic film (1869)
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3.091SC Introduction to Solid State ChemistryFall 2009
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