Question

What is the hybridization of the underlined nitrogen atom in each of the following molecules or ions? a. \(\mathrm{NO}^{+}\) b. \(\mathrm{N}_{2} \mathrm{O}_{3}\left(\mathrm{O}_{2} \mathrm{NNO}\right)\) c. \(\mathrm{NO}_{2}^{-}\) d. \(\mathrm{N}_{2}\)

Short answer

The hybridization of the underlined nitrogen atoms in the given molecules or ions are: a. \(\mathrm{NO}^{+}\): sp b. \(\mathrm{N}_{2} \mathrm{O}_{3}\left(\mathrm{O}_{2} \mathrm{NNO}\right)\): sp2 c. \(\mathrm{NO}_{2}^{-}\): sp3 d. \(\mathrm{N}_{2}\): Exception (No hybridization)

Step-by-step solution

Determine the Electron Domains for Each Nitrogen Atom

(For each molecule/ion, we will determine the number of electron domains around the nitrogen atom to help us find its hybridization.) a. In \(\mathrm{NO}^{+}\), the nitrogen atom forms two bonds (one with the oxygen). Hence, it has two electron domains. b. In \(\mathrm{N}_{2} \mathrm{O}_{3}\left(\mathrm{O}_{2} \mathrm{NNO}\right)\), the central nitrogen atom forms three bonds (one with the other nitrogen atom and two with the oxygen atoms). Thus, it has three electron domains. c. In \(\mathrm{NO}_{2}^{-}\), the central nitrogen atom forms three bonds (two with the oxygen atoms) and has one lone pair of electrons. Consequently, it has four electron domains. d. In \(\mathrm{N}_{2}\), each nitrogen atom forms a triple bond with the other nitrogen atom. So, each nitrogen atom has one electron domain.

Determine the Hybridization of Each Nitrogen Atom

(Now that we know the number of electron domains for each nitrogen atom, we can determine their hybridization using the following rules: 2 electron domains - sp, 3 electron domains - sp2, 4 electron domains - sp3.) a. The nitrogen atom in \(\mathrm{NO}^{+}\) has two electron domains, hence it is sp hybridized. b. The central nitrogen atom in \(\mathrm{N}_{2} \mathrm{O}_{3}\left(\mathrm{O}_{2} \mathrm{NNO}\right)\) has three electron domains, hence it is sp2 hybridized. c. The nitrogen atom in \(\mathrm{NO}_{2}^{-}\) has four electron domains, hence it is sp3 hybridized. d. The nitrogen atom in \(\mathrm{N}_{2}\) has one electron domain, making it an.Exception (No hybridization). To summarize: a. \(\mathrm{NO}^{+}\): sp hybridization b. \(\mathrm{N}_{2} \mathrm{O}_{3}\left(\mathrm{O}_{2} \mathrm{NNO}\right)\): sp2 hybridization c. \(\mathrm{NO}_{2}^{-}\): sp3 hybridization d. \(\mathrm{N}_{2}\): Exception (No hybridization)

Key concepts

Electron Domains

In chemistry, understanding electron domains is key to predicting molecular shapes and hybridization states. Electron domains are essentially regions where electrons are most likely to be found within a molecule. These regions can consist of:

• Bonding pairs (single, double, or triple bonds between atoms).
• Lone pairs (non-bonding pairs of electrons).

To determine the hybridization of any atom, you first need to count these electron domains around the atom. For example, in the molecule \(\mathrm{NO}^{+}\), the nitrogen atom has two electron domains because it forms two bonds. This information is crucial, as it guides us to the correct hybridization state of the atom.

sp Hybridization

sp hybridization occurs when an atom is surrounded by two electron domains. This type of hybridization involves the mixing of one s orbital with one p orbital, resulting in two sp hybrid orbitals. These orbitals are linear, with a bond angle of 180 degrees, indicating that the electron domains are oriented as far as possible from one another.An example of sp hybridization is found in the nitrogen atom of \(\mathrm{NO}^{+}\). Here, the nitrogen atom forms a linear shape, as it is bound to another atom through two domains. This efficient, linear arrangement minimizes electron domain repulsions.

sp2 Hybridization

When an atom is surrounded by three electron domains, it undergoes sp2 hybridization. During this process, one s orbital combines with two p orbitals to form three sp2 hybrid orbitals. These orbitals arrange themselves in a trigonal planar configuration, with bond angles of 120 degrees.The central nitrogen atom in \(\mathrm{N}_{2} \mathrm{O}_{3}\left(\mathrm{O}_{2} \mathrm{NNO}\right)\) provides a segment example. Here, the nitrogen forms three bonds, making it sp2 hybridized. This arrangement allows for an even distribution of the electron domains and optimally angles them apart, ensuring structural stability.

sp3 Hybridization

sp3 hybridization occurs in atoms with four electron domains. In this form, one s orbital and three p orbitals mix to create four equivalent sp3 hybrid orbitals. These orbitals adopt a tetrahedral shape, with bond angles close to 109.5 degrees.The nitrogen atom in \(\mathrm{NO}_{2}^{-}\) is sp3 hybridized. In this structure, the nitrogen atom has two bonds and one lone pair, accounting for four electron domains. The tetrahedral geometry is slightly distorted due to the lone pair, but the sp3 hybridization efficiently describes the overall electron domain arrangement.