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Subatomic particles

Subatomic particles inside an atomSubatomic particles inside an atom An atom is the smallest part of an element that can exist. But an atom is not the smallest thing there is. Inside it are even smaller, subatomic particles. Most of these cluster together in the tiny nucleus at the centre of the atom: protons and neutrons (the other subatomic particles are electrons). A very powerful force keeps these two kinds of particles together. It is called the strong nuclear force and operates at the tiny distances found within the nucleus. When atomic nuclei collide and join, or fuse, together, as happens inside the Sun, the strong nuclear force is released as massive amounts of energy. Energy can also be released when atomic nuclei are split apart (nuclear fission), as happens in nuclear power stations.

Quarks (blue and white balls) and gluons (gold)Quarks (blue and white balls) and gluons (gold)


Incredibly, protons and neutrons are themselves formed from still smaller particles, called quarks. Protons and neutrons both contain three quarks, but they contain a different balance of two kinds of quark, known as “up” or “down”. Neutrons contain one up quark and two down quarks, while protons contain two up quarks and one down quark. Protons can readily change into neutrons, and vice versa, by changing one of their quarks. The quarks are held together by other types of subatomic particles, called gluons.
Particle tracks, created by high-speed collisionsParticle tracks, created by high-speed collisions

Higgs boson

Protons are about 2000 times heavier than electrons.

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