Question

Which types of atomic orbitals of the central atom mix to form hybrid orbitals in (a) \(\mathrm{SiClH}_{3} ;\) (b) \(\mathrm{CS}_{2} ;\) (c) \(\mathrm{SCl}_{3} \mathrm{~F} ;\) (d) \(\mathrm{NF}_{3} ?\)

Short answer

(a) \( sp^3 \), (b) \( sp \), (c) \( sp^3d \), (d) \( sp^3 \).

Step-by-step solution

- Understand the concept of hybridization

Hybridization is the process where atomic orbitals mix to form new hybrid orbitals, which can form sigma bonds with other atoms. The type of hybridization depends on the steric number, which is the sum of bonded atoms and lone pairs around the central atom.

- Determine the steric number for \( \text{SiClH}_3 \)

For \( \text{SiClH}_3 \), silicon is the central atom with three hydrogen atoms and one chlorine atom bonded. Silicon has no lone pairs. Steric number = 4. Therefore, the hybridization is \( sp^3 \).

- Determine the steric number for \( \text{CS}_2 \)

For \( \text{CS}_2 \), carbon is the central atom with two sulfur atoms bonded. Carbon forms two double bonds and has no lone pairs. Steric number = 2. Therefore, the hybridization is \( sp \).

- Determine the steric number for \( \text{SCl}_3 \text{F} \)

For \( \text{SCl}_3 \text{F} \), sulfur is the central atom with three chlorine atoms and one fluorine atom bonded. Sulfur also has one lone pair. Steric number = 5. Therefore, the hybridization is \( sp^3d \).

- Determine the steric number for \( \text{NF}_3 \)

For \( \text{NF}_3 \), nitrogen is the central atom with three fluorine atoms bonded. Nitrogen also has one lone pair. Steric number = 4. Therefore, the hybridization is \( sp^3 \).

Key concepts

atomic orbitals

Atomic orbitals are regions around an atom where electrons are likely to be found. These orbitals come in different shapes and sizes. The most common atomic orbitals include the s, p, d, and f orbitals. Each type has its unique characteristics.
For instance, s orbitals are spherical, while p orbitals have a dumbbell shape. d and f orbitals have even more complex shapes.
These orbitals can overlap with orbitals from other atoms to form bonds in a molecule.
In molecules, atomic orbitals mix and match to make new, hybrid orbitals that help in bonding and determining the shape of the molecule.

steric number

The steric number is a crucial concept for understanding hybridization. It helps you determine the hybridization state of an atom in a molecule.
The steric number is found by adding the number of atoms bonded to the central atom and the number of lone pairs on that central atom.
For example, in \(\text{SiClH}_3\), the central atom (Si) is bonded to three hydrogen atoms and one chlorine atom. There are no lone pairs. So the steric number is 4.
This steric number gives a clue on the type of hybridization the central atom will have.

sigma bonds

Sigma bonds (σ bonds) are the strongest type of covalent chemical bonds. They form when atomic orbitals overlap head-on.
These bonds are crucial in the structure of molecules, as they allow atoms to stick together by sharing electrons.
In a sigma bond, the electron density is highest along the axis connecting the two bonding nuclei.
For instance, in \(\text{CS}_2\), the carbon and sulfur atoms are connected via sigma bonds, which are pivotal in holding the molecule together.

sp^3 hybridization

sp^3 hybridization happens when one s orbital mixes with three p orbitals. This mixing creates four hybrid orbitals, each equivalent in energy and shape.
Molecules with a steric number of 4 often have sp^3 hybridization.
For example, in \(\text{SiClH}_3\), silicon under sp^3 hybridization forms a tetrahedral shape with bond angles close to 109.5°.

sp hybridization

sp hybridization happens when one s orbital mixes with one p orbital. This forms two sp hybrid orbitals that are 180° apart.
Molecules with a steric number of 2 typically show sp hybridization.
A good example is \(\text{CS}_2\) where the central carbon atom forms two sp hybrid orbitals, creating a linear molecule.

sp^3d hybridization

sp^3d hybridization occurs when one s orbital, three p orbitals, and one d orbital mix. This results in five hybrid orbitals.
Molecules with a steric number of 5 show sp^3d hybridization.
For instance, \(\text{SCl}_3 \text{F}\) has sulfur with sp^3d hybridization, forming a trigonal bipyramidal structure.