Protons

A proton is a subatomic particle found in the nucleus of every atom, carrying a positive electric charge. Along with neutrons, protons form the dense core around which electrons orbit. The number of protons in an atom defines its element—hydrogen has one, helium has two, and so on up the periodic table.

Protons are remarkably stable and nearly 2,000 times heavier than electrons, yet they occupy a space roughly 100,000 times smaller than the atom itself. This strange contrast hints at the bizarre geometry of the quantum realm. Protons are made of even tinier constituents called quarks, bound together by the strong nuclear force.

Understanding protons unlocked modern physics. Their discovery by Ernest Rutherford in 1919 revealed that atoms have structure—a revolutionary insight. Today, protons are essential to chemistry, nuclear physics, and technologies ranging from medical imaging to particle accelerators.

The proton's charge defines electrical behavior across all of chemistry and biology, making it one of nature's most consequential fundamental particles.

Related

Atomic structure, Nucleus (atom), Rutherford scattering, Particle physics, Hydrogen atom