Question

Identify the hybridization state for the nitrogen atom in ammonia \(\left(\mathrm{NH}_{3}\right)\)

Short answer

The nitrogen atom in ammonia is sp^3 hybridized.

Step-by-step solution

Determine the Valence Electrons

First, we need to find the number of valence electrons in the nitrogen atom. Nitrogen is in group 15 of the periodic table and has 5 valence electrons.

Count the Bonds and Lone Pairs

In ammonia ( NH_3 ), nitrogen forms three single bonds with hydrogen atoms and has one lone pair of electrons remaining.

Calculate the Steric Number

The steric number is the sum of the number of atoms bonded to the nitrogen (3 hydrogen atoms) and the number of lone pairs of electrons on nitrogen (1 lone pair). Thus, the steric number is 4.

Determine the Hybridization

Hybridization is determined based on the steric number: if the steric number is 4, the hybridization is sp^3 . Therefore, the nitrogen atom in ammonia is sp^3 hybridized.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom and play a crucial role in chemical bonding. They determine how an atom interacts and forms bonds with other atoms. For nitrogen, which is in group 15 of the periodic table, there are 5 valence electrons. This is essential information because these electrons participate in forming bonds with hydrogen atoms in ammonia ( H_3 ). Understanding the number of valence electrons helps us predict the atom's behavior and its ability to form bonds, giving insights into molecular structures.

Steric Number

The steric number is a valuable concept in determining the hybridization of an atom. It is calculated by adding the number of atoms bonded to the central atom and the number of lone pairs present on that atom. In our example with ammonia ( H_3 ), the nitrogen atom is bonded to three hydrogen atoms and has one lone pair. This makes the steric number equal to 4 (3 bonds + 1 lone pair). A steric number of 4 indicates that the hybridization is sp^3 , which suggests a tetrahedral geometry for the electron groups around nitrogen.

sp3 Hybridization

sp^3 hybridization occurs when one s orbital and three p orbitals mix to form four new equivalent orbitals. Each of these orbitals has the same energy level and orientation. This type of hybridization is common in molecules like ammonia ( H_3 ), where the nitrogen atom has a steric number of 4. The mixing of orbitals allows the nitrogen atom to form four sigma bonds, three with hydrogen atoms and one occupied by a lone pair. Understanding sp^3 hybridization is crucial for explaining the shape and bonding properties of a molecule.

Lone Pairs

Lone pairs are unshared pairs of electrons found in the outer shell of an atom. In ammonia ( H_3 ), the nitrogen atom has one lone pair. These pairs do not participate in bonding but influence the molecule's shape and its polarity. The lone pair on nitrogen pushes the bonded hydrogen atoms closer, creating a trigonal pyramidal shape instead of a perfect tetrahedral. Thus, lone pairs are significant as they affect the overall geometry and reactivity of a molecule.

Chemical Bonding

Chemical bonding is the process where atoms share or transfer valence electrons to achieve a stable electron configuration. In ammonia, nitrogen forms single covalent bonds with three hydrogen atoms by sharing its valence electrons. This sharing results in sigma bonds, which are a type of covalent bond characterized by head-on orbital overlap. Chemical bonds in molecules like ammonia are essential for maintaining the structure and stability of the compounds we encounter in chemistry. Understanding these bonds helps us comprehend the foundational principles of molecular interactions.