# Calling compounds electron deficient [closed]

I believe this is a conceptual question and might sound silly, but please help me with it:

I can understand when ions like $$\text{Co}^{3+},\text{Mg}^{2+}$$ are called electron deficient, because they have no valence electrons, but how do I call a compound like $$\text{AlCl}_3$$ electron deficient? What's the basis for calling such a compound electron deficient?

## closed as off-topic by Mithoron, Todd Minehardt, A.K., Jannis Andreska, aventurinFeb 9 at 16:46

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• Is aluminium's octet complete? – Avnish Kabaj Feb 4 at 10:44
• Yeah, I believe aluminium's octet is complete. – Dhrubajyoti Ghosh Feb 4 at 11:05
• @DhrubajyotiGhosh No, it's not. Count the valence electrons again. – andselisk Feb 4 at 12:07
• Being electron-deficient would imply that the molecule possesses vacant MO which can feasibly accept electrons from an effective Lewis base. And yes, AlCl3 has an incomplete octect(6 electons). – William R. Ebenezer Feb 4 at 12:13
• @DhrubajyotiGhosh No, it's not silly, it's fine. Only the one who does nothing is never mistaken. You can post an answer to your question if you solved the issue yourself:) – andselisk Feb 5 at 13:05