What is the oxidation state of Aluminum (Al) in most compounds?

What is the oxidation state of Aluminum (Al) in most compounds?

• A. +2
• B. +3
• C. +1
• D. 0

Answer: (B)

Oxidation states are a bookkeeping tool to track electrons in bonds. Aluminum sits in group 13 and has three valence electrons. The most stable way for aluminum to satisfy its valence is to lose those three electrons, forming Al3+. That gives it a noble-gas electron configuration and explains why it commonly appears as Al3+ in compounds like AlCl3 or Al2O3. In a neutral element, oxidation state is 0, which is why metallic aluminum has 0 but compounds very rarely show +1 or +2 for aluminum—those states are not typical of its chemistry. So the standard oxidation state of aluminum in most compounds is +3.

Oxidation states are a bookkeeping tool to track electrons in bonds. Aluminum sits in group 13 and has three valence electrons. The most stable way for aluminum to satisfy its valence is to lose those three electrons, forming Al3+. That gives it a noble-gas electron configuration and explains why it commonly appears as Al3+ in compounds like AlCl3 or Al2O3. In a neutral element, oxidation state is 0, which is why metallic aluminum has 0 but compounds very rarely show +1 or +2 for aluminum—those states are not typical of its chemistry. So the standard oxidation state of aluminum in most compounds is +3.