What is an isotope?

An isotope is a variant of a chemical element that has the same number of protons but different numbers of neutrons.

In more detail, every element on the periodic table is defined by the number of protons in its nucleus, known as its atomic number. For example, all carbon atoms have 6 protons. However, atoms of the same element can have different numbers of neutrons. These different versions are called isotopes. For instance, carbon-12 has 6 neutrons, while carbon-14 has 8 neutrons. Both are isotopes of carbon because they have the same number of protons.

Isotopes can be stable or unstable. Stable isotopes do not change over time, while unstable isotopes, also known as radioactive isotopes, decay over time and emit radiation. This property makes radioactive isotopes useful in a variety of applications, such as carbon dating in archaeology, where carbon-14 is used to determine the age of ancient objects.

The presence of different isotopes can affect the atomic mass of an element. The atomic mass listed on the periodic table is a weighted average of all the naturally occurring isotopes of that element. For example, chlorine has two main isotopes, chlorine-35 and chlorine-37, and its atomic mass is an average that takes into account the relative abundance of each isotope.

Understanding isotopes is crucial in fields like chemistry, physics, and environmental science. They help scientists trace chemical pathways, understand nuclear reactions, and even diagnose medical conditions through techniques like PET scans. So, while isotopes are just variations of elements, their unique properties make them incredibly important in both scientific research and practical applications.