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3. Atomic Models: Rutherford & Bohr

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Session Overview

Modules Structure of the Atom
Concepts Thomson's plum pudding model, Rutherford's model of the nucleus, Bohr's model of the hydrogen atom, Rutherford-Geiger-Marsden experiment, Planck-Einstein relationship, isotopes of hydrogen
Keywords lanthanides, actinides, electron, mass, J. J. Thomson, proton, electrical charge, amber, alpha particle, beta particle, ionization, conservation of mass, Johannes Geiger, Ernest Marsden, coulomb, Niels Bohr, Bohr model of hydrogen, energy quantization, orbital angular momentum, Planck-Einstein relationship, joule, Newtonian force, Coulombic force, Max Planck, photon, energy, frequency, Planck's constant, isotope, Henry Cavendish, Harold Urey, Ernest Rutherford, blackbody radiation
Chemical Substances

lanthanum (La), magnesium (Mg), chlorine (Cl), titanium (Ti), helium (He), hydrogen (H)

Applications nuclear fission, nanotechnology

Prerequisites

Before starting this session, you should be familiar with:

Looking Ahead

Prof. Sadoway discusses the atomic spectra of hydrogen (Session 4).

Learning Objectives

After completing this session, you should be able to:

  • Understand Thomson's "plum pudding" model.
  • Understand Rutherford's "nuclear" model.
  • Explain the Bohr model of hydrogen.
  • Understand Bohr's quantization condition.

Reading

Archived Lecture Notes #1 (PDF), Sections 1-3

Book Chapters Topics
[A&E] 1.5, "The Atom." The electron; radioactivity; the atomic model
[A&E] 6.2, "The Quantization of Energy." Blackbody radiation; the photoelectric effect
[A&E] 6.3, "Atomic Spectra and Models of the Atom." Line spectra; the Bohr model; uses of emission and absorption spectra

Lecture Video

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Resources

This resource may not render correctly in a screen reader.Lecture Slides (PDF - 9.3MB)

Periodic Table and Table of Constants

Transcript (PDF)

Lecture Summary

Prof. Sadoway talks about the principles of modern chemistry and how that led to the understanding of the structure of the atom. He details Bohr's postulates for the hydrogen atom and discusses how the Planck-Einstein relationship applies to electron transitions. He defines the different isotopes of hydrogen.

This lecture includes the following:

  • J. J. Thomson's "plum pudding" model
    • Electrons are distributed uniformly throughout the atom
  • Ernest Rutherford's "nuclear" model
    • Conclusions from the gold foil experiment
    • Majority of the mass is found in the nucleus
    • Electrons orbit around the nucleus
  • Niels Bohr's quantization condition
    • Explanation of blackbody radiation and atomic spectra
    • Postulates:
      • Electrons follow circular orbits around a nucleus
      • Orbital angular momentum is quantized hence only certain orbits are possible
      • Electrons in stable orbits do not radiate
      • Electrons change orbits by radiating or absorbing photons

Homework

Problems (PDF)

Solutions (PDF)

Textbook Problems

[A&E] Sections Conceptual Numerical
[A&E] 1.5, "The Atom." none 4
[A&E] 1.6, "Isotopes and Atomic Masses." none 10
[A&E] 6.1, "Waves and Electromagnetic Energy." none 8
[A&E] 6.2, "The Quantization of Energy." none 3, 6

For Further Study

Textbook Study Materials

See the [A&E] companion website from Pearson for PowerPoint outlines of each chapter, plus online quizzes, interactive graphs and 3D molecular animations:

Supplemental Readings

Buy at Amazon Ottaviani, J. Suspended in Language: Niels Bohr's Life, Discoveries, and the Century He Shaped. GT Labs: Ann Arbor, MI, 2004. ISBN: 9780978803728.

Buy at Amazon Rozental, S. Niels Bohr: His Life and Work as Seen by His Friends and Colleagues. New York, NY: Wiley, 1967.

Buy at Amazon Bohr, Niels H. D. On the Constitution of Atoms and Molecules. New York, NY: W.A. Benjamin, 1963.

Buy at Amazon Bohr, Niels H. D. Atomic Physics and Human Knowledge. New York, NY: Wiley, 1958.

Bohr, Niels. "On the Constitution of Atoms and Molecules." Philosophical Magazine Series 6 26 (July 1913): 1-15.

Buy at Amazon Cathcart, B. The Fly in the Cathedral: How a Small Group of Cambridge Scientists Won the Race to Split the Atom. New York, NY: Penguin, 2005. ISBN: 9780670883219.

Buy at Amazon Andrade, E. N. Rutherford and the Nature of the Atom. Garden City, NY: Doubleday, 1964.

Buy at Amazon Frayn, M. Copenhagen: A Play in Two Acts. New York, NY: S. French, 2000.

Buy at Amazon Miller, D. P. Discovering Water: James Watt, Henry Cavendish and the Nineteenth Century Water Controversy. Burlington, VT: Ashgate, 2004. ISBN: 9780754631774.

Cavendish Laboratory

How Atoms Work

People

Joseph Thompson - 1906 Nobel Prize in Physics

Ernest Rutherford - 1908 Nobel Prize in Chemistry

Johannes Geiger

Ernest Marsden

Max Planck - 1918 Nobel Prize in Physics

Albert Einstein - 1921 Nobel Prize in Physics

Niels Bohr - 1922 Nobel Prize in Physics

Robert Millikan - 1923 Nobel Prize in Physics

Henry Cavendish

Werner Heisenberg - 1932 Nobel Prize in Physics

Harold Urey - 1934 Nobel Prize in Chemistry

Charles-Augustin de Coulomb

James Prescott Joule

Other OCW and OER Content

Content Provider Level Notes
5.111 Principles of Chemical Science MIT OpenCourseWare Undergraduate (first-year)

Lecture 2: Discovery of Electron and Nucleus

Lecture 5: Hydrogen Atom Energy Levels

The Bohr Model HyperPhysics High school  

 

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