Electronic structure

• Electrons

  Electrons that move in shells (sometimes called energy levels)
• Electron shells


  • The inner shells are always filled up first
  • Only certain number of electrons are allowed in each shell: 1st shell: 2, 2nd shell: 8, 3rd shell: 8
  • Atoms are a lot more stable when they have full electron shells
  • In most atoms, the outer shell is not full
• Electron structures can be shown as diagrams or as numbers like 2.8.2
• Working out electronic structures


  1. Follow the Electron Shell Rules

  2. Can easily work out the electronic structures for the first 20 elements of the periodic table