Organic Chemistry MCAT Practice Exam 2025 – The All-in-One Guide to Master Your Test Preparation!

In an amine, the nitrogen atom is bonded to three hydrogen atoms or to a combination of hydrogen and carbon atoms. To determine the hybridization of nitrogen in this context, we can consider its molecular geometry and bonding.

Nitrogen has five valence electrons and typically forms three bonds when it acts as a center in an amine. This results in one lone pair of electrons on the nitrogen. The geometry associated with nitrogen forming three single bonds (with a bond angle of about 109.5 degrees) and one lone pair is tetrahedral.

The hybridization that accommodates this tetrahedral shape is sp3. In sp3 hybridization, one s orbital combines with three p orbitals, resulting in four equivalent hybrid orbitals, which can form sigma bonds with other atoms. Therefore, in amines where nitrogen is bonded to three substituents and has one lone pair, it is indeed sp3 hybridized.

This sp3 hybridization allows nitrogen to efficiently create the three sigma bonds necessary to bond with other atoms while also accommodating the lone pair. Hence, this is why the correct answer is that the hybridization of the nitrogen atom in an amine is sp3.