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 |
|---|---|
| [Saylor] 1.5, “The Atom.” | The electron; radioactivity; the atomic model |
| [Saylor] 6.2, “The Quantization of Energy.” | Blackbody radiation; the photoelectric effect |
| [Saylor] 6.3, “Atomic Spectra and Models of the Atom.” | Line spectra; the Bohr model; uses of emission and absorption spectra |
Lecture Video
Resources
Periodic Table and Table of Constants
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
Textbook Problems
| [Saylor] Sections | Conceptual | Numerical |
|---|---|---|
| [Saylor] 1.5, “The Atom.” | none | 4 |
| [Saylor] 1.6, “Isotopes and Atomic Masses.” | none | 10 |
| [Saylor] 6.1, “Waves and Electromagnetic Energy.” | none | 8 |
| [Saylor] 6.2, “The Quantization of Energy.” | none | 3, 6 |
For Further Study
Supplemental Readings
Ottaviani, J. Suspended in Language: Niels Bohr’s Life, Discoveries, and the Century He Shaped. GT Labs: Ann Arbor, MI, 2004. ISBN: 9780978803728.
Rozental, S. Niels Bohr: His Life and Work as Seen by His Friends and Colleagues. New York, NY: Wiley, 1967.
Bohr, Niels H. D. On the Constitution of Atoms and Molecules. New York, NY: W.A. Benjamin, 1963.
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.
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.
Andrade, E. N. Rutherford and the Nature of the Atom. Garden City, NY: Doubleday, 1964.
Frayn, M. Copenhagen: A Play in Two Acts. New York, NY: S. French, 2000.
Miller, D. P. Discovering Water: James Watt, Henry Cavendish and the Nineteenth Century Water Controversy. Burlington, VT: Ashgate, 2004. ISBN: 9780754631774.
People
Joseph Thompson - 1906 Nobel Prize in Physics
Ernest Rutherford - 1908 Nobel Prize in Chemistry
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
Werner Heisenberg - 1932 Nobel Prize in Physics
Harold Urey - 1934 Nobel Prize in Chemistry
Other OCW and OER Content
| Content | Provider | Level | Notes |
|---|---|---|---|
| 5.111 Principles of Chemical Science | MIT OpenCourseWare | Undergraduate (first-year) | |
| The Bohr Model | HyperPhysics | High school |
