Octet rule and its limits
The key idea
The octet rule is a useful introductory pattern: many main-group atoms form arrangements associated with eight valence-shell electrons.
Why it matters
It is a guide, not a universal law. Electron-deficient species, odd-electron species and expanded-valence descriptions remind us where the shortcut stops working.
A picture to remember
It is a guide, not a universal law. Electron-deficient species, odd-electron species and expanded-valence descriptions remind us where the shortcut stops working.