Electron Configuration
Science: KS3, topic 2.3.4
Electronic Structure
Electrons have fixed positions in atoms called shells or energy levels. These shells (or energy levels) go around the atom's nucleus.
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Filling electron shells
- Electrons fill an atom's shells in order of increasing energy.
- The closer a shell is to the nucleus, the lower its energy level, so the first shell that is filled is the closest to the nucleus.
Electron configuration
- Electron configuration tells us how an atom's electrons are organised.
- The innershell (closest to the nucleus) can have a maximum of 2 electrons and the next two shells can have a maximum of 8 electrons.
- Any extra electrons are then put into a fourth shell.
Test yourself on Electron Configuration
How many more electrons can fit in the 2nd electron shell compared to the 1st?
Select the true statement in each pair.
Electrons fill an atom's shells in order of increasing energy, with shells closer to the nucleus having lower energy. Why is the first shell filled with electrons before the second shell?