Draw the Lewis structure for BeCl2.

The Lewis structure is a visual representation of how valence electrons are arranged among atoms in a molecule. It helps predict the bonding, molecular geometry, and reactivity of the compound. Beryllium chloride (BeCl\(_2\)) is a linear molecule composed of one beryllium (Be) atom and two chlorine (Cl) atoms.

## 2. Step-by-Step Construction of the Lewis Structure for BeCl\(_2\)

Step 1: Determine the Total Number of Valence Electrons

1. Beryllium (Be) belongs to Group 2, meaning it has 2 valence electrons.

2. Chlorine (Cl) belongs to Group 17, meaning each Cl atom has 7 valence electrons.

3. Since there are two chlorine atoms, the total number of valence electrons contributed by Cl is: \[ 2 \times 7 = 14 \]

4. Adding the contributions from Be and Cl, the total number of valence electrons in BeCl\(_2\) is: \[ 2 + 14 = 16 \]

Step 2: Draw the Skeletal Structure

- Beryllium (Be) is the central atom because it is the least electronegative.

- The two chlorine (Cl) atoms are placed on opposite sides of Be.

Step 3: Place Single Bonds Between Be and Cl

Each single bond consists of two electrons:

Since we have two Be–Cl bonds, we use: \[ 2 \times 2 = 4 \text{ electrons} \]

After placing the bonds, we subtract these electrons from the total: \[ 16 - 4 = 12 \text{ electrons remaining} \]

Step 4: Distribute the Remaining Electrons as Lone Pairs

- The remaining 12 electrons are placed around the two chlorine atoms to complete their octets.

- Each Cl atom needs 8 valence electrons, but each already has 2 from the Be–Cl bond.

- Thus, each Cl atom needs 6 more electrons, which are placed as lone pairs.

Each chlorine atom has 8 valence electrons (including bonding and lone pairs), satisfying the octet rule.

Step 5: Check the Stability of the Structure

- Each chlorine (Cl) atom has a full octet.

- Beryllium (Be) has only 4 valence electrons, which is an exception to the octet rule.

- Be is an electron-deficient element, meaning it is stable with four valence electrons in some compounds like BeCl\(_2\).

## 3. Molecular Geometry of BeCl\(_2\)

Using Valence Shell Electron Pair Repulsion (VSEPR) theory, we analyze the molecular geometry:

1. Number of electron domains around Be: 2 bonding pairs, 0 lone pairs.

2. Electron domain geometry: Linear.

3. Predicted bond angle:

\[ 180^\circ \]

Thus, BeCl\(_2\) is a linear molecule with a bond angle of 180°.

## 4. Summary of the BeCl\(_2\) Lewis Structure and Molecular Properties

\[
\begin{array}{|c|c|}
\hline
\textbf{Property} & \textbf{Value} \\
\hline
\textbf{Central Atom} & \text{Beryllium (Be)} \\
\hline
\textbf{Valence Electrons in BeCl}_2 & 16 \\
\hline
\textbf{Lone Pairs on Be} & 0 \\
\hline
\textbf{Lone Pairs on Each Cl} & 3 \\
\hline
\textbf{Electron Geometry} & \text{Linear} \\
\hline
\textbf{Molecular Geometry} & \text{Linear} \\
\hline
\textbf{Bond Angle} & 180^\circ \\
\hline
\textbf{Octet Rule Exception} & \text{Be has only 4 valence electrons} \\
\hline
\end{array}
\]

## 5. Conclusion

The Lewis structure of BeCl\(_2\) shows beryllium forming two single bonds with chlorine, resulting in a linear molecular geometry. BeCl\(_2\) does not follow the octet rule, as beryllium is stable with only four valence electrons. This structure is crucial in understanding the bonding of electron-deficient molecules and is commonly observed in beryllium halides and other Group 2 metal halides.