Keywords |
  • Chemistry


The atom is the fundamental building block of matter. A substance composed of atoms of the same kind is called a chemical element.

- a nucleus of nucleons: protons and neutrons where practically the entire mass of the atom is concentrated,
- electrons, very small, orbiting far from the nucleus.

The size of the atom: of the order of 10-10 m

The smallest atom is that of hydrogen: 1 single proton, 1 electron.



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