What is Nuclear Energy? - Definition & Examples

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  • 0:06 What is Nuclear Energy?
  • 0:50 What are Nuclear Reactions?
  • 1:43 What Do Nuclear…
  • 4:15 Lesson Summary
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Lesson Transcript
Instructor: John Simmons

John has taught college science courses face-to-face and online since 1994 and has a doctorate in physiology.

You've probably heard of nuclear energy. But what is it? And what is the difference between fusion and fission? This lesson will answer your questions about this exciting form of energy that involves atoms and their nuclei.

What Is Nuclear Energy?

Energy is the ability to do work, where work is the movement of something when an effort is applied. We need and we use energy in our lives every day. We use energy to contract our muscles and move our cars. We use energy to warm our homes and toast our bread. Scientists are busy researching new ways to make energy available for our use. The sun seems an inexhaustible source of energy. Energy from the sun lights the sky and warms the planet. The energy from the sun is a type of nuclear energy or energy created from nuclear reactions.

During nuclear fusion, the contents of the nucleus change.
Nuclear Reaction Changes Nucleus

What Are Nuclear Reactions?

That's easy enough, but what are nuclear reactions? Before we can define a nuclear reaction, we need to explore the basic structure of an atom. Atoms are the smallest building blocks of matter, and matter is anything that has mass and takes up space. Different atoms make up different elements; for example, hydrogen, helium, gold and silver are all elements. Each atom contains a nucleus, and the nucleus contains protons and neutrons. Electrons surround the nucleus of an atom. A nuclear reaction is a reaction that changes the nucleus of an atom. In other words, the number of protons and/or neutrons is changed as a result of a nuclear reaction.

What Do Nuclear Reactions Have to Do with Energy?

So what does this have to do with energy? The answer is simple and yet, amazingly profound. Nuclear reactions release energy. That statement is so important, I'll repeat it. Nuclear reactions release energy, and they release a lot of it! There are two types of nuclear reactions. Fission occurs when large nuclei are split into smaller fragments. Fusion occurs when small nuclei are put together to make a bigger one. Here's the amazing thing. Either way - whether it's fusion or fission - energy is released as a result of the nuclear reaction.

Let's look at an example of each type of nuclear reaction. Nuclear fission is used to generate electricity in our nuclear power plants. Fission occurs when uranium nuclei are bombarded with neutrons. The neutrons hit and split the uranium nuclei into fragments. The fission releases a lot of energy and other neutrons as well. Those other neutrons, in turn, cause a chain reaction and cause other uranium nuclei to split, and additional energy is released. Nuclear power plants can generate a lot of electricity from a very small amount of uranium and no pollution released into the atmosphere. Nuclear fission, however, produces radioactive waste that is harmful to life and has to be properly stored.

Nuclear fusion is the process of small nuclei combining to form a bigger one.
Nuclear Fusion Diagram

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