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This "online textbook" is designed to provide a thorough, in-depth treatment of this topic at the first-year college or advanced-HS levels, with a special focus on the underlying concepts. Please note that some of these pages require a standards-compliant browser such as Firefox, Opera or Safari; they will not display properly in Netscape Navigator or in some versions of Internet Explorer.

> Click one of the six lesson titles immediately below on the left;
> you can also go directly to any sub-section within a lesson.

1- Quanta: a new view of the world

The limits of classical physics The quantum revolution Radiation is quantized The photoelectric effect Matter and energy united concept map | Max Planck and Albert Einstein

2- Light, particles and waves

The language of light Light a particle: the photon Light as electromagnetic radiation Spectra: interaction of light with matter Wavelength of a particle The uncertainty principle concept map |

3- The Bohr atom

The atom before Bohr Bohr's orbital model Spectrum of a guitar string Standing waves in the hydrogen atom The hydrogen spectrum explained Emission and absorption spectrum; Fraunhofer lines concept map |

4- The quantum atom

The wave function and its physical meaning Why doesn't the electron fall into the nucleus? Quantum numbers of electrons in atoms Electron spin and the Pauli exclusion principle concept map |

5- Atomic electron configurations

Atoms that have only one electron Effects of electron-electron repulsion The Aufbau rules The periodic table concept map |

6- Periodic properties of the elements

How the periodic table is organized The shell model of the atom Effective nuclear charge Sizes of atoms and ions Ionization energies Electron affinities Electronegativity References and periodic table links concept map |

Among the many sources the author drew upon, special mention should be made of Pimentel and Spratley’s Understanding Chemistry, S. Brush’s Introduction to Concepts and Theories in Physical Science, P. Atkin’s Quanta, P. Davies’ The Forces of Nature, and the inspired writing of Toulmin and Goodfield in The Architecture of Matter.