Electronic Structure

• Where are the electrons located in an atom?

  Electrons are found in shells (or ’energy levels‘), and orbit the nucleus
• What do we mean by the ’electronic structure’ or ‘electronic configuration’ of an atom?

  The arrangement of electrons within an atom, i.e. how many electrons are in each shell
• How many electrons are found in the first, second, and third shells of an atom?

  1st shell: 2 electrons, 2nd shell: 8 electrons, 3rd shell: 8 electrons
• If an atom has 15 electrons in total, how many will it have in each shell?


  2 in the first shell, 8 in the second shell and 5 in the third shell
• What is meant by an atoms ’outer shell‘?

  The shell of electrons that is further from the nucleus