The simple diagram above presents a schematic picture of an atom. It consists of three kinds of particles, and it's depicted that protons have a positive charge and are situated in the very center of an atom together with neutrons, particles with no charge. This dense region is called a nucleus, and electrons, which are lighter and have a negative charge, fly around it in a small cloud.

When the number of protons is equal to the number of electrons, the atom is called a normal atom. An atom works as a magnet: the electrical force keeps it together, attracting negative electrons to the positive nucleus.

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