Everything you see, touch, and breathe is made up of tiny building blocks called atoms. You can think of atoms as the smallest type of LEGO brick, and when you connect these bricks together in different ways, you can build everything in the universe. Each type of atom is a specific element, like oxygen or gold, and it has its own unique identity that determines what it can build.
The Atomic Recipe: Defining Identity
Every atom is built from three even smaller particles: protons, neutrons, and electrons. Protons have a positive electrical charge and live in the atom’s dense center, called the nucleus. The number of protons determines the element’s identity. For example, any atom with six protons is always carbon, and changing that number instantly turns it into a different element.
Neutrons also live inside the nucleus but have no electrical charge. Electrons, which have a negative charge, zoom around the nucleus in shells. Since protons and neutrons are much heavier than electrons, their combined total gives an atom its mass number.
Isotope Definition: Atoms with Extra Weight
An isotope is a version of an element that has the same number of protons but a different number of neutrons. Imagine a specific model of a car (the element) that always has the same engine (protons). Sometimes, the factory adds extra weight (neutrons) to the frame, making it a heavier version of the same model.
Isotopes are atoms that are chemically identical because they have the same number of protons and electrons, but they have a slightly different physical mass. Most isotopes have a stable nucleus, meaning they stay together forever without changing. However, some isotopes have too many neutrons and become unstable, like Carbon-14, and are called radioisotopes.
These unstable atoms naturally break down over time, a process known as radioactive decay. As they decay, they release energy and matter (radiation) while trying to achieve a more stable balance of particles. This difference in stability and mass allows scientists to use isotopes in many helpful ways.
Isotope Examples and Why They Matter
Carbon is a perfect example of how isotopes work, existing mainly as Carbon-12 and Carbon-14. Both are carbon because they each have six protons, but Carbon-12 has six neutrons, while the heavier Carbon-14 has eight neutrons. The stable Carbon-12 makes up nearly all the carbon found in nature.
The unstable Carbon-14 has a fixed rate of decay that scientists use to determine the age of ancient organic materials. This process, called carbon dating, allows researchers to figure out how old a piece of wood, bone, or fossil is by measuring how much Carbon-14 remains in the sample.
Other isotopes are used in medicine as tracers. Doctors can inject a small amount of a radioisotope, and the energy it emits allows special cameras to create images of organs or detect disease.
For instance, certain iodine isotopes help doctors check the function of the thyroid gland, while others are used to target and destroy cancerous cells.