Question

Explain the structure of ${\mathrm{BeCl}}_2$ with the help of hybridization.

Short answer

Question: Based on the hybridization concept, describe the structure of ${\mathrm{BeCl}}_2$. Answer: The structure of ${\mathrm{BeCl}}_2$ is linear, with beryllium at the center forming single covalent bonds with two chlorine atoms at an angle of 180 degrees using its two $\mathrm{sp}$ hybrid orbitals.

Step-by-step solution

Electron Configuration of Be and Cl

Determine the electron configuration of beryllium and chlorine. Beryllium has 4 electrons, and its electron configuration is $1{\mathrm{s}}^{2}2{\mathrm{s}}^2$. Chlorine has 17 electrons, with an electron configuration of $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^5$.

Type of Hybridization

Identify the type of hybridization in ${\mathrm{BeCl}}_2$. In the case of ${\mathrm{BeCl}}_2$, beryllium forms two single bonds with each of the chlorine atoms. To form these bonds, the two electrons in beryllium's 2s orbital get excited and hybridize with its vacant 2p orbitals. This results in the formation of two $\mathrm{sp}$ hybrid orbitals.

The Structure of ${\mathrm{BeCl}}_2$

Determine the structure of ${\mathrm{BeCl}}_2$ based on hybridization. The two $\mathrm{sp}$ hybrid orbitals of beryllium are now available for bonding. The hybrid orbitals are arranged linearly at an angle of 180 degrees, resulting in a linear molecular structure for ${\mathrm{BeCl}}_2$. The beryllium atom lies at the center with chlorine atoms on either side, forming single covalent bonds using their 3p orbitals.

Key concepts

Hybridization

Hybridization is a fundamental chemical concept that explains the bonding in molecules, especially when it comes to determining molecular geometry. In the case of ${\text{BeCl}}_2$, hybridization helps us understand how beryllium (Be) bonds with chlorine (Cl) atoms.
BeCl2 undergoes $\text{sp}$ hybridization, which means that one s orbital mixes with one p orbital, resulting in two equivalent $\text{sp}$ hybrid orbitals. This type of hybridization is essential in creating bonds that are more stable than they would be without hybridization.
Key Points about Hybridization:

• Makes bonding more efficient
• Creates hybrid orbitals of equal energy
• Poduces a specific geometry to the molecule

The result is crucial for forming molecules like BeCl2 that involve central atoms making multiple bonds with surrounding atoms. Understanding hybridization provides insight into the shape and stability of molecules.

Beryllium Electron Configuration

The electron configuration of beryllium is essential to understand its role in ${\text{BeCl}}_2$.
Beryllium has 4 electrons, and its standard electron configuration is $1{\text{s}}^{2}2{\text{s}}^2$. This means all electrons are initially located in s orbitals.
However, in order to form bonds in ${\text{BeCl}}_2$, one of the electrons from the filled 2s orbital needs to be promoted to an empty 2p orbital. This seemingly simple shift is pivotal as it allows beryllium to undergo $\text{sp}$ hybridization.
Key Points on Beryllium Electron Configuration:

• Total electrons: 4
• Regular configuration: $1{\text{s}}^{2}2{\text{s}}^2$
• Post-promotion configuration: $1{\text{s}}^{2}2{\text{s}}^{1}2{\text{p}}^1$

Understanding this electron promotion helps us see why and how beryllium can form the necessary covalent bonds with chlorine atoms.

Chlorine Electron Configuration

Chlorine, an element in Group 17 of the periodic table, has 17 electrons. Its electron configuration is $1{\text{s}}^{2}2{\text{s}}^{2}2{\text{p}}^{6}3{\text{s}}^{2}3{\text{p}}^5$.
This configuration reveals that chlorine has seven valence electrons, one short of achieving a stable octet. This is why chlorine readily forms bonds with other elements like beryllium.
Chlorine uses its single unpaired 3p electron to form a bond with the electron in beryllium's $\text{sp}$ hybrid orbitals. This interaction is vital in forming ${\text{BeCl}}_2$.
Key Points on Chlorine Electron Configuration:

• Total electrons: 17
• Valence electrons: 7 ($3{\text{s}}^{2}3{\text{p}}^5$)
• Bonding point: 3p orbitals

Recognizing chlorine's electron configuration is crucial as it highlights the electron sharing necessary for molecule formation.

SP Hybrid Orbitals

Hybrid orbitals are integral to the formation of molecular bonds and their subsequent shapes. When beryllium forms ${\text{BeCl}}_2$, it uses $\text{sp}$ hybrid orbitals.
Here's how $\text{sp}$ hybridization works in ${\text{BeCl}}_2$:

• One 2s and one 2p orbital from beryllium mix to form two new $\text{sp}$ orbitals
• These $\text{sp}$ orbitals are oriented 180 degrees apart, promoting a linear structure
• The two $\text{sp}$ hybrid orbitals form sigma (σ) bonds with the lone 3p orbitals of chlorine atoms

This hybridization process explains the efficient bonding and the resulting stability of ${\text{BeCl}}_2$. It's crucial for achieving the desired molecular geometry.

Linear Molecular Structure

The concept of linear molecular structure is central to understanding the shape of ${\text{BeCl}}_2$. This structure is predicted and explained by $\text{sp}$ hybridization.
Linear structures occur when molecules adopt a straight-line shape, with bond angles close to 180 degrees, as seen in ${\text{BeCl}}_2$. This arrangement minimizes electron pair repulsion.
For ${\text{BeCl}}_2$:

• The central beryllium atom, with its two $\text{sp}$ hybrid orbitals, aligns these orbitals in opposite directions
• The chlorine atoms bond at either end, leading to a linear molecular shape
• Both the efficient use of hybrid orbitals and the minimization of repulsive forces contribute to this structure

This simple yet important structural arrangement leads to the unique chemical properties observed in ${\text{BeCl}}_2$, such as its angle and symmetry.