Electron ArrangementElectrons are arranged in the shell of atoms around the nucleusElectrons occupy the shells closest to the nucleus firstThe electrons only start occupying a new shell when the previous one has been occupied

NucleusThe 1st shell : 2 electronsThe 2nd shell : 8 electronsThe 3rd shell : 8 electronsThe 4th shell : 2 electronsElectron Arrangement

Lithium2.1Carbon2.4

Nitrogen2.5Oxygen2.6

Sodium2.8.1Magnesium2.8.2

Valence ElectronThe electron in the outermost occupied shell

Neon2.8Valence Electron : 8Aluminium2.8.3Valence Electron : 3

Fluorine2.7Valence Electron : 7Silicon2.8.4Valence Electron : 4

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