Particle

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This is an atom, and it is very small. Atoms are made up of particles. Red circles represent protons and blue circles represent neutrons. The atom shown here is a helium atom.

Particles are tiny bits of matter that make up everything in the universe. In particle physics, an elementary particle is a particle which cannot be split up into smaller pieces.

There are many different types of particles, all with different sizes and properties.

Three particles which are all around us are the proton, the neutron, and the electron. These are the particles which make atoms. The proton has a positive charge (a + charge). The neutron has a neutral charge. The electron has a negative charge (a - charge), and it is the smallest of these three particles. In atoms, there is a small nucleus in the center, which is where the protons and neutrons are, and electrons orbit the nucleus.

Protons and neutrons are not elementary particles because they are made up of quarks. There are six different types of quarks. These are the up quark, the down quark, the strange quark, the charm quark, the bottom quark, and the top quark. A neutron is made of two down quarks and one up quark. The proton is made up of two up quarks and one down quark.