Problem 3 - Chemistry A Guided Inquiry

Question

One of the resonance structures for the nitrate ion, \(\mathrm{NO}_{3}^{-}\), is shown below. What is the predicted O-N-O bond angle? What is the expected hybridization of the nitrogen atom?

Step-by-Step Solution

Answer

The predicted O-N-O bond angle of Nitrate ion \(\mathrm{NO}_{3}^{-}\) is approximately 120 degrees and the Nitrogen atom is sp2 hybridized.

Step 1: Understand Nitrate Ion Structure

Analyze the structure of Nitrate ion \(\mathrm{NO}_{3}^{-}\). Nitrate ion consists of a Nitrogen atom surrounded by three Oxygen atoms in a trigonal planar configuration and carry one extra electron.

Step 2: Predict O-N-O Bond Angle

Based on the VSEPR theory, the molecule takes the shape that places the electron pairs as far apart as possible to minimise the repulsion. If you suppress one of the oxygen atoms and observe the structure from the side, you will see that there is trigonal planar geometry around nitrogen atom (N); hence the Nitrogen-Oxygen-Nitrogen (O-N-O) bond angle will be approximately 120 degrees.

Step 3: Determine the Hybridization of Nitrogen Atom

The hybridization of an atom can be found by adding the number of atoms connected to it and the number of lone pairs of electrons. Nitrogen in Nitrate ion is bonded to three oxygen atoms and has no lone pairs. Therefore, there are three orbitals in hybridization and hence, the hybridization is sp2.