Nuclear Physics

A series of free Online High School Physics Video Lessons.

In this lesson, w will learn

  • Atomic Nucleus
  • Nuclear Stability
  • Nuclear Reactions
  • Alpha Decay



Atomic Nucleus

The atomic nucleus was discovered by Earnest Rutherford in his Gold Foil Experiment in which he shot alpha particles at a thin piece of gold foil. Most of the particles went straight through the foil, but a few bounced straight back. This told him that there must be small compact positive units inside the atom. This is the atomic nucleus, a small core which contains most of an atom's mass but makes up only a 100,000th of the atom's total volume. The ratio of protons to neutrons in an atomic nucleus affects an atom's stability and can cause radioactive decay.

 Understanding the structure and history of the atomic nucleus

This video describes Rutherford's (Geiger-Marsden's) discovery of the nucleus and the ideas that formed their hypothesis and the reformation of the atomic model from the results and its implications for further understanding of atomic structure



Nuclear Stability

Nuclear stability is what makes certain isotopes radioactive. An isotope is unstable if it has a ratio of protons to neutrons that isn’t within what is called the “band of stability”. Elements with atomic numbers greater than 70 are never stable. Unstable isotopes generally undergo transmutation, alpha decay, or beta decay.

How the ratio of protons to neutrons affects a nucleus' stability.

A good introductory video on nuclear stability.



Nuclear Reactions

Nuclear reactions are reactions between nuclei which involve tremendous amounts of energy and in which mass number and charge are conserved. Alpha and beta decay, fission and fusion are all types of nuclear reactions. Unlike chemical reactions, atomic number is usually changed.

The different types of nuclear reactions.

In nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial



Alpha Decay

Alpha Decay is a type of radioactivity in which the nucleus of an atom loses an alpha particle. Alpha particles are composed of two protons and two neutrons, so they can also be called He2+ nuclei. The result of alpha decay is the transformation of an element into an element found two boxes before it on the periodic table.

Understanding the alpha decay of radioactive substances.

Alpha decay is a type of radioactive (nuclear) decay. This video explains what alpha decay is, how atoms go from stable to unstable, and shows practice problems with examples of alpha decay.




Custom Search


We welcome your feedback, comments and questions about this site - please submit your feedback via our Feedback page.


© Copyright 2005, 2012 -
Embedded content, if any, are copyrights of their respective owners.

Useful Links:
More Geometry Help on MathWorld





Custom Search