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Chemistry for Kids

Radioactivity


Stable and Unstable Isotopes

Elements can be made up of different isotopes. Isotopes are atoms with the same number of protons and electrons, but a different number 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 radioactive isotopes. 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 radiation or radioactive decay depending on the isotope.

Different Types of Radioactivity How is it measured?

Radioactivity is measured using a unit called the "curie". It is abbreviated as "Ci". The curie measures how many atoms spontaneously decay each second. The curie was 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 time on average that 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 these atoms are expected to decay over the course of 5730 years. Some of the atoms may decay right away, while others will not decay for many thousands more 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 one specific sample. It is just what will happen on average over the course of billions and billions of atoms.

Radioactive Decay to other Elements

When isotopes decay they can lose some of their atomic particles (i.e. electrons and protons) and turn from one element into another. Sometimes isotopes decay from one unstable isotope into another unstable isotope. This can happen continuously in a long radioactive chain.

An example of a radioactive chain is uranium-238. As it decays, it transforms through a number of elements including thorium, radium, francium, radon, polonium, and bismuth. It finally ends up as a stable isotope as the element lead.

Why is radiation dangerous?

Radiation can alter the structure of cells in our bodies causing mutations which 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 a number of good ways that science has used radiation. These include X-rays, medicine, carbon dating, energy generation, and to kill germs.

Interesting Facts about Radioactivity Activities

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More Chemistry Subjects

Matter
Atom
Molecules
Isotopes
Solids, Liquids, Gases
Melting and Boiling
Chemical Bonding
Chemical Reactions
Radioactivity and Radiation
Mixtures and Compounds
Naming Compounds
Mixtures
Separating Mixtures
Solutions
Acids and Bases
Crystals
Metals
Salts and Soaps
Water
Other
Glossary and Terms
Chemistry Lab Equipment
Organic Chemistry
Famous Chemists

Elements and the Periodic Table
Elements
Periodic Table

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