CHEMISTRY - ELECTRON SHELLS
- Created by: SJC
- Created on: 16-05-13 18:47
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- Electron shells
- Electron shell rules:
- 1) Electrons always occupy shells ( sometimes called energy levels).
- 2) The lowest energy levels are always filled first- these are the ones closest to the nucleus
- 3) Only a certain number of electrons are allowed in each shell:
- 1st shell: 2, 2nd shell: 8, 3rd shell: 8
- 4) Atoms are much happier when they have a full electron shells- like the noble gases in group 0.
- 5) In most atoms the outer shell is not and this makes the atom want to react
- Follow the rules to work out electron configurations
- 1) The periodic table tells us nitrogen has seven protons..... so it must have seven electrons
- 2) Follow the 'Electon shell rules'. The first shell can only take 2 electrons and the second shell can take a maximum of 8 electrons
- 3) so the electron configuration for nitrogen must be 2,5.
- Electron shell rules:
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