Since then, as Visual Capitalist's Govind Bhutada and Mark Belan detail below, the global nuclear stockpile has multiplied, and when geopolitical tensions rise, the idea of a nuclear apocalypse understandably causes widespread concern.

But despite their catastrophically large effects, the science of how nuclear weapons work is atomically small...

The Atomic Science of Nuclear Weapons

All matter is composed of atoms, which host different combinations of three particles—protons, electrons, and neutrons. Nuclear weapons work by capitalizing on the interactions of protons and neutrons to create an explosive chain reaction.

At the center of every atom is a core called the nucleus, which is composed of closely-bound protons and neutrons. While the number of protons is unique to each element in the periodic table, the number of neutrons can vary. As a result, there are multiple "species" of some elements, known as isotopes.

For example, here are some isotopes of uranium:

Uranium-238: 92 protons, 146 neutrons

Uranium-235: 92 protons, 143 neutrons

Uranium-234: 92 protons, 142 neutrons

These isotopes can be stable or unstable. Stable isotopes have a relatively static or unchanging number of neutrons. But when a chemical element has too many neutrons, it becomes unstable or fissile.

When fissile isotopes attempt to become stable, they shed excess neutrons and energy. This energy is where nuclear weapons get their explosivity from.