Second order hybridization question – would Nitrogen be sp or sp2 hybridized if it has 1 bonded Hydrogen, 1 lone pair, and a double bond to Carbon that is double bonded to another Carbon? Would the lone pair participate in the hybridization making it sp2 or would it want to pi conjugate with the 2 sp double bonded carbons and be sp also
The Correct Answer and Explanation is:
Answer:
The nitrogen atom is sp² hybridized.
Explanation:
The hybridization of an atom is determined by the number of regions of electron density (also called steric number) surrounding it, which includes both sigma bonds and lone pairs. In this case, the nitrogen atom is bonded to one hydrogen atom via a sigma bond, one carbon atom via a sigma bond that is part of a double bond (the pi bond does not count toward hybridization), and possesses one lone pair. This gives nitrogen a steric number of 3 (1 sigma bond to hydrogen + 1 sigma bond to carbon + 1 lone pair), which corresponds to sp² hybridization.
The double bond between nitrogen and carbon consists of one sigma bond (formed by overlap of sp² orbitals) and one pi bond (formed by the side-on overlap of unhybridized p orbitals). The lone pair on nitrogen occupies one of the sp² hybrid orbitals. This lone pair does not participate in conjugation with the adjacent carbon-carbon double bond directly because its orbital orientation is orthogonal to the p orbitals involved in the pi system of the C=C bond, unless there is an extended conjugated system, which is not indicated in this case.
Had the nitrogen been sp hybridized, it would require only two regions of electron density, such as in a linear arrangement with one triple bond or two double bonds. However, the presence of both a lone pair and two sigma bonds dictates an sp² hybridization. Furthermore, sp² hybridization allows the nitrogen to maintain a trigonal planar geometry, which is favorable for overlap with the adjacent carbon’s p orbital to form the N=C pi bond.
Thus, based on the electron domain count and bonding pattern, the nitrogen is sp² hybridized.
