Outer Shell
Key Stage 3
Meaning
A diagram showing the three electron shells of a Sodium atom. The outer shell is the electron orbital furthest from the nucleus.
The outer shell is the electron orbital furthest from the nucleus of an atom.
About the Outer Shell
- The outer shell is the only electron orbital that is affected in chemical reactions.
- The number of electrons in the last Outer Shell determines the Group on the Periodic Table.
- The outer shell is the highest energy level in an atom.
- Electrons in the outer shell may gain enough energy from collisions or from electromagnetic radiation to leave the atom producing a free electron and turning the atom into an ion.
- Ionising Radiation can cause electrons to leave the outer shell leaving behind a positively charged ion.
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| This diagram shows that the number of electrons in the outer shell determines which group the elements have been placed into in the Periodic Table. NB Group 0 used to be called Group 8 but this caused confusion because most elements in Group 8 have 8 electrons in their Outer Shell but Helium only has 2, so it was renamed Group 0. |