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Atomic Structure

Explore simplified atomic models. Select an element to inspect its nucleus, electron arrangement, atomic number, and mass number.

Atom visualizer

Proton Neutron Electron

Model limitation

Electron shells are drawn as circles to make atomic structure easier to study. Real electrons do not travel along these fixed circular paths; quantum mechanics describes their probable locations using orbitals.

Element explorer

Choose an element This explorer uses a common isotope for each listed element.

Electron animation speed 1× Adjust the speed of the illustrative electron animation.

Atomic number 1

Mass number 1

Protons 1

Neutrons 0

Electrons 1

Net charge 0

Electron arrangement by shell

Remember

Atomic number = number of protons. For a neutral atom, the number of electrons equals the number of protons.

Mass number = number of protons + number of neutrons.