Electron Shells

Electron Shells

1. Electrons are arranged in shells around the nucleus of the atom

2. When drawing electron shells, you write the chemical symbol in the middle then draw spherical circles on the outside with crosses (electrons)

3. electronic configuration: the way in which electrons are arranged in an atom

   • Finding configuration
     • Different shells can contain different electrons, but the shells can only hold a certain amount of electrons on each spherical circle
       • For the first 20 elements the first shell can contain upto two electrons
         • In the second and third shells atom can hold up to eight, although the third can hold more that this
     • Electronic configuration can be wrote down instead of using diagrams, the configuration for carbon is 2.4, because it has 6 electrons and there can only be 2 on the first shell and there are 4 left to be on the 2nd shell

4. Atomic number is shown to represent the number of protons and electrons in an atom

   • If the atomic number of sodium is 11, then it means there are 11 protons and 11 electrons, you can draw the electronic configuration shells to represent the number of electrons on each shell

5. Spotting connections

   • apart from the noble gasses in group zero, there are connections between the outer shell and where they are positioned in the periodic table. In group one sodium has the electron configuration of 2.8.1 and potassium below has the configuration of 2.8.8.1 meaning that both have electrons on their very outer shell