Atomic structure - (CCEA)The atomic model

Atoms have a positively-charged nucleus made of protons and neutrons, and negatively-charged electrons that orbit the nucleus in shells.

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The atomic model

In 1932, James Chadwick discovered the – a particle with no charge in the nucleus of the atom.

Structure of a carbon atom, with a proton, neutron and electron labelled
Figure caption,
The modern model of the atom.

Today, scientists use an atomic model that has a central, positively-charged nucleus that contains:

  • positively-charged
  • neutral neutrons

Negatively-charged electrons orbit the nucleus in shells.

An atom’s nucleus gives it most of its mass.