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What Are Radioactive Materials? - Definition, Examples, Uses & Benefits

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  • 0:01 What Is Radioactivity?
  • 2:03 Alpha, Beta, & Gamma Rays
  • 3:07 Radioactive Materials…
  • 4:27 Benefits & Harm of Radiation
  • 5:50 Lesson Summary
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Lesson Transcript
Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Radioactive materials are all around us. Some are beneficial, while others may cause us harm. In this lesson you'll learn what radioactive materials are and explore where they come from and how they can be useful to us.

What Is Radioactivity?

Everything on Earth is made of atoms, but you can see that not everything on Earth is the same. This is because everything is made of different types of atoms called elements. Atoms are really, really, REALLY small, but each atom of an element is made of even smaller subatomic particles. These are the protons, neutrons, and electrons of the atom.

The number of protons determines what element that atom is. For example, an atom with 8 protons is always oxygen, and an atom with 80 protons is always mercury. If you change the number of protons, you change the element.

One thing that can change though is the number of neutrons. Let's look at carbon for example. A carbon atom will always have 6 protons, but it may have 6, 7, or 8 neutrons. These atoms are carbon isotopes, because they are atoms of the same element that have different numbers of neutrons.

When isotopes are unstable, meaning that they have an imbalance of neutrons and protons, they are radioactive. The carbon atom with 6 neutrons, also called carbon-12 since we just add up the number of protons and neutrons to get its name, and the carbon atom with 7 neutrons, also called carbon-13, are both stable. This is because the number of protons and neutrons is in good balance.

The carbon atom with 8 neutrons (you guessed it - carbon-14) is not stable, though. This atom is radioactive because it has too much energy, making it unstable. After a while, the extra energy will be released from the unstable atom. This process is called radioactive decay. After enough energy is released, the atom returns to a stable state and is no longer radioactive. All radioactive materials eventually decay, just not at the same rate.

Alpha, Beta, & Gamma Rays

The extra energy, or radiation, emitted by radioactive elements comes in three different types: alpha, beta, and gamma. Alpha radiation is a stream of alpha particles, which are positively charged. They're fairly large, which means they have a difficult time getting through materials like clothes and paper.

Beta radiation is a stream of beta particles, which are negatively charged. These particles can more easily penetrate materials like clothes, and they can even get deep into your skin where they can do harm to your cells. But they can be blocked with denser materials like aluminum.

Gamma radiation is high-frequency electromagnetic radiation. Gamma rays have no charge but have A LOT of energy; more energy than even visible light or X-rays. Because of this, they are able to pass right through most materials, making them quite dangerous. But they can't penetrate very dense materials like lead, which is why you may be given a lead vest for protection in a hospital or laboratory.

Radioactive Materials Are Natural

Most people think of radioactive materials as harmful, man-made materials, but quite the opposite is true. In fact, most radioactive materials occur naturally in the environment and have been around much longer than humans!

Most of the radiation we're exposed to on Earth comes from the sun and stars in outer space. We are constantly bombarded with this radiation but we're partially protected from it by the atmosphere around us. Those at sea level are more protected than those at higher altitudes because the protective atmosphere thins with increasing elevation. In fact, someone in Denver receives twice as much of this type of radiation than someone at sea level!

Radiation also comes from other things like rocks and minerals. Because of this, those who live in houses made of brick, concrete, or stone receive a greater amount of radiation than those who live in houses made of wood.

Believe it or not, your body is also a culprit of radiation! Much of this comes from the potassium we eat - but that doesn't mean you should stop taking in this vital nutrient! The isotope potassium-40 is a beta-ray emitter, and about 5000 of these atoms decay radioactively in your body with every beat of your heart!

Benefits & Harm of Radiation

The reason you're more familiar with man-made radiation is because it has provided numerous benefits to humans. X-ray and CT machines, medical sterilization equipment, smoke detectors, cancer treatments, food sterilization, and medical diagnostic tests are just a few ways that humans have harnessed the power of radiation in a positive way.

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