What is Radioactivity? | Types, Definition, Structure, Function & Facts

What is Radioactivity?

Radioactivity is the process by which the nucleus of an unstable atom loses energy by emitting ionizing radiation. As each nucleus decays, it produces a charged particle with enough kinetic energy to pass through solid matter. The act of spontaneously emitting radiation, as the name suggests, is known as radioactivity. An unstable atomic nucleus for some reason “wants” to give up energy in favor of a more stable configuration that achieves this.

Stable and Unstable Isotopes

Elements can be made up of different isotopes. Isotopes are atoms that have the same number of protons and electrons but different numbers of neutrons. Sometimes isotopes are stable and happy. These are the elements that we see around us and find in nature. However, some isotopes are unstable. These isotopes are called radioisotopes. You can go here to learn more about isotopes.

What is Radioactive Decay?

When isotopes are unstable, they emit energy in the form of radiation. There are three main types of radioactivity or radioactive decay depending on the isotope.

Different Types of Radioactivity

Alpha Decay – Alpha decay is caused when there are too many protons in the nucleus. In this case, the element will emit radiation in the form of positively charged particles called alpha particles.

Beta Decay – Beta decay is caused when there are too many neutrons in the nucleus. In this case, the element will emit radiation in the form of negatively charged particles called beta particles.

Gamma Decay – Gamma decay occurs when there is too much energy in the nucleus. In this case, gamma particles with no overall charge are emitted from the element.

How is it measured?

Radioactivity is measured in a unit known as “curie”. It is abbreviated as “Ci”. Curie measures how many atoms spontaneously decay every second. The Curia is named after Marie and Pierre Curie, who discovered the element radium.

What is the half-life of an Isotope?

The half-life of an isotope is the average time it takes for half of the atoms in a sample to decay.

For example, the half-life of carbon-14 is 5730 years. This means that if you have a sample of carbon-14 with 1,000 atoms, 500 of them will decay over the course of 5,730 years. Some atoms may decay immediately, while others will not decay for several thousand years.

The thing to remember about half-life is that it is a probability. In the example above, 500 atoms are “expected” to decay. This is not a guarantee for a particular model. This is exactly what happens on average over trillions of atoms.

Radioactive Decay to other Elements

When isotopes decay, they can lose some atomic particles (i.e. electrons and protons) and change from one element to another. Sometimes isotopes decay from one unstable isotope to another. It can occur continuously over a long radioactive sequence.

An example of a radioactive sequence is uranium-238. When it decomposes, it turns into a number of elements, including thorium, radium, francium, radon, polonium, and bismuth. It eventually becomes a stable isotope as the lead element.

Why is Radiation Dangerous?

Radiation can change the structure of cells in our body, causing mutations that can produce cancer. The more radiation a person is exposed to, the more dangerous it is.

Is some Radiation Good?

Despite the risks, there are some good ways that science has used radiation. These include X-rays, medicine, carbon dating, energy production, and germ killing.

Interesting Facts about Radioactivity

Uranium in the ground can decompose into radon gas, which is very dangerous for humans. It is believed to be the second leading cause of lung cancer.

The half-life of carbon-14 is used in carbon dating to determine the age of fossils.

Bismuth is the heaviest element with at least one stable isotope. All elements heavier than bismuth are radioactive.