Which element can only show a +3 oxidation state?

CONCEPT:

Oxidation States of Transition Elements

• Transition metals exhibit multiple oxidation states because they have unfilled d-orbitals and can lose different numbers of electrons.
• Elements like Scandium (Sc), Titanium (Ti), Iron (Fe), and Cobalt (Co) can show variable oxidation states, depending on their chemical environment.
• The +3 oxidation state is a common oxidation state for many transition metals, but not all transition metals can only exist in this state.

EXPLANATION:

• Scandium (Sc): Scandium can only exhibit a +3 oxidation state. After losing its 3 valence electrons (2 from the 4s and 1 from the 3d), it achieves a stable noble gas configuration (similar to Argon), and no other oxidation states are accessible.
• Titanium (Ti): Titanium can show multiple oxidation states, including +2, +3, and +4, making it more versatile in its chemistry.
• Iron (Fe): Iron commonly shows +2 and +3 oxidation states but can also exhibit other oxidation states in complex compounds.
• Cobalt (Co): Cobalt can display multiple oxidation states, with +2 and +3 being the most common.

CONCLUSION:

• Scandium (Sc) is the only element from the given list that can only exist in the +3 oxidation state.