Nuclear Physics

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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 explains how the structure of the nucleus influences the properties of the atom. The number of the protons determines the kind of element. Isotopes are formed when the number of protons remain the same but the neutrons are different. Some isotopes are radioactive and may decay over time. The rate of decay is the half-life and can be used to measure decay or time. 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. Contrasts nuclear reactions to chemical reactions. Explains the four main forces of nature; including gravity, electromagnetism, strong, and weak nuclear forces. It also explains how fusion differs from fission. 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.