Problem 91 - Chemistry An Atoms First Approach

Question

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

Step-by-Step Solution

Answer

The hybridization states of the underlined nitrogen atoms in the given molecules or ions are: a. \(NO^{+}\): sp b. \(O_2NNO (N_2O_3)\): sp² c. \(NO_2^{-}\): sp² d. \(N_2\): sp²

Step 1: Finding Steric Number

Determine the steric number for each nitrogen atom (defined as the number of bond pairs and lone pairs around it): a. NO⁺ b. O₂NNO (N₂O₃) c. NO₂⁻ d. N₂

Step 2: Determining Hybridization

Find the hybridization state of the underlined nitrogen atom in each molecule/ion using the steric number calculated from Step 1. a. NO⁺

Step 2a: Steric Number for NO⁺

In the case of NO⁺, there are two atoms bonded to the nitrogen (O and N⁺) and no lone pairs. So the steric number of the nitrogen is 2.

Step 2b: Hybridization of NO⁺

If the steric number is 2, the hybridization will be sp. Therefore, the hybridization of the underlined nitrogen atom in NO⁺ is sp. b. O₂NNO (N₂O₃)

Step 2c: Steric Number for N₂O₃

In the case of N₂O₃, there are three atoms bonded to the nitrogen atom (2 O atoms and 1 N atom) and no lone pairs. So the steric number of the nitrogen is 3.

Step 2d: Hybridization of N₂O₃

If the steric number is 3, the hybridization will be sp². Therefore, the hybridization of the underlined nitrogen atom in N₂O₃ (O₂NNO) is sp². c. NO₂⁻

Step 2e: Steric Number for NO₂⁻

In the case of NO₂⁻, there are two atoms bonded to the nitrogen atom (2 O atoms) and one lone pair. So the steric number of the nitrogen is 3.

Step 2f: Hybridization of NO₂⁻

If the steric number is 3, the hybridization will be sp². Therefore, the hybridization of the underlined nitrogen atom in NO₂⁻ is sp². d. N₂

Step 2g: Steric Number for N₂

In the case of N₂, there is one atom bonded to the nitrogen atom (another N atom) and two lone pairs. So the steric number of the nitrogen is 3.

Step 2h: Hybridization of N₂

If the steric number is 3, the hybridization will be sp². Therefore, the hybridization of the underlined nitrogen atom in N₂ is sp².

Key Concepts

Steric Number

The concept of the "Steric Number" is crucial in understanding the hybridization of atoms in molecules. It tells us how crowded an atom is with bonds and lone pairs. To calculate it, you add up all the atoms directly bonded to the atom in question and also include any lone pairs of electrons.
For example:

• If an atom has 2 atoms bonded to it and no lone pairs, the steric number is 2.
• If it has 2 atoms bonded and 1 lone pair, the steric number becomes 3.

This number will then guide you in determining the type of hybridization required to accommodate this arrangement. Therefore, the steric number provides a straightforward method to predict molecular geometry and hybridization.

Nitrogen Compounds

Nitrogen compounds are a diverse group of chemical substances where nitrogen atoms are bonded to various other elements. Nitrogen can form compounds by sharing its electrons to bond with other atoms, such as oxygen or carbon.
Some common nitrogen compounds are nitrates, ammonium, and oxides of nitrogen, each showing different chemical properties due to their unique structures.
Understanding nitrogen compounds' structuring helps predict their behaviors in chemical reactions and their physical properties. The hybridization state of nitrogen in a compound noticeably affects the geometry and type of bonds formed, influencing the overall stability and reactivity of the compound.

Chemical Bonding

Chemical bonding involves the joining of atoms to form molecules. This occurs when atoms share or transfer electrons to achieve stable electron arrangements. Nitrogen atoms can form single, double, or triple bonds, depending on the compound:

• Single bonds occur when only one pair of electrons is shared between two atoms.
• Double bonds involve two pairs of shared electrons.
• Triple bonds, seen in nitrogen gas ( ₂), involve three pairs of electrons and are very strong.

This diversity in bonding is controlled by hybridization, dictating the shape of the molecule and how it will interact with others. A thorough grasp of bonding is vital for predicting molecular behavior and properties in various chemical contexts.

SP Hybridization

SP hybridization happens when one s orbital mixes with one p orbital to form two equivalent sp orbitals. This type of hybridization is associated with a linear geometry around the central atom and a steric number of 2.
For instance, in nitric oxide cation ( ⁺), the nitrogen shows sp hybridization due to bonding with one oxygen and holding a positive charge without lone pairs. This configuration can result in molecules that are very reactive due to their highly directed orbitals, influencing their participation in chemical reactions.
It’s an important concept to grasp as it sets the foundation for understanding how molecular shape and bond angles arise from atomic orbitals.

SP² Hybridization

SP² hybridization, or 'sp squared' hybridization, occurs when one s orbital and two p orbitals mix to create three equivalent sp² orbitals. This usually results in a trigonal planar shape around the central atom and a steric number of 3.
In molecules like dinitrogen trioxide (N₂O₃), the nitrogen can achieve sp² hybridization, allowing it to form bonds with three neighboring atoms. This hybridization often results in planar molecules with bond angles of about 120 degrees, which can influence things like reactivity and molecular polarity.
Understanding sp² hybridization helps predict the molecular geometry and how compounds interact, especially for reactions that depend on the geometry of molecules.