Nuclear PhysicsA series of free High School Physics Video Lessons from Brightstorm online Physics series.
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.
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.
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.
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.
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