Question

Predict the geometry of sulfur dichloride \(\left(\mathrm{SCl}_{2}\right)\) and the hybridization of the sulfur atom.

Short answer

SCl2 has a bent geometry and sulfur is sp3 hybridized.

Step-by-step solution

Determine the Valence Electrons

Sulfur ( \(\mathrm{S}\) ) has 6 valence electrons, and each chlorine ( \(\mathrm{Cl}\) ) atom has 7 valence electrons. Since there are two chlorine atoms, the total number of valence electrons is: \(6 + 2 \times 7 = 20\) electrons.

Draw the Lewis Structure

With 20 valence electrons, draw the Lewis structure for \(\mathrm{SCl}_{2}\) . Place sulfur in the center, bind two chlorine atoms to it, and complete octets for each atom. There will be 2 lone pairs remaining on sulfur after these bonds and the chlorines satisfy their octets.

Determine the Geometry Using VSEPR Theory

According to VSEPR theory, the geometry depends on the number of bonded atoms and lone pairs around the central atom (sulfur). With 2 bonds and 2 lone pairs, use the VSEPR type AX2E2, which corresponds to a bent or angular shape.

Identify the Hybridization of Sulfur

Based on the VSEPR model, sulfur uses hybrid orbitals. With 4 regions of electron density (2 single bonds and 2 lone pairs), sulfur is \(\mathrm{sp}^{3}\) hybridized, as it needs four equivalent orbitals to accommodate these areas.

Key concepts

VSEPR theory

The VSEPR theory, or Valence Shell Electron Pair Repulsion theory, is a model used to predict the geometry of molecules. The main idea is that electron pairs around a central atom will repel each other.

• Because of this repulsion, the molecule will arrange itself in a way that minimizes these repulsions, optimizing the space between the electron pairs.
• This theory helps us determine the shape of a molecule based on the number of bonded atoms and lone pairs around the central atom.

In the case of sulfur dichloride (\(\mathrm{SCl}_{2}\)), sulfur acts as the central atom. It has 2 chlorine atoms bonded to it and 2 lone pairs. According to VSEPR theory, this combination results in a bent or angular shape. This corresponds to the VSEPR notation AX2E2, where "A" represents the central atom, "X" represents the bonded atoms, and "E" represents the lone pairs.

Lewis structure

The Lewis structure is a visual representation to show how valence electrons are arranged in a molecule. For sulfur dichloride (\(\mathrm{SCl}_{2}\)), it helps us understand how the atoms are bonded and where the lone pairs reside.

• First, count the total number of valence electrons involved in the molecule. Sulfur has 6, and each chlorine has 7, resulting in a total of 20 valence electrons.
• Next, arrange the atoms with sulfur in the center and connect each chlorine atom with a single bond. This uses up 4 valence electrons, leaving us with 16 for lone pairs and bonding.
• Assign remaining electrons to satisfy the Octet Rule, prioritizing outer atoms first - here, the chlorine atoms.
• The leftover electrons form lone pairs around the central sulfur atom.

For \(\mathrm{SCl}_{2}\), this results in a structure where sulfur is bonded to two chlorines and has two lone pairs, helping explain its bent shape.

hybridization

Hybridization is a concept that explains how atomic orbitals mix to form new hybrid orbitals, which are used in bonding with other atoms. For sulfur dichloride (\(\mathrm{SCl}_{2}\)), sulfur undergoes \(\mathrm{sp}^{3}\) hybridization.

• This hybridization occurs because sulfur needs to make two sigma bonds (with the chlorine atoms) and also accommodate two lone pairs of electrons.
• In \(\mathrm{sp}^{3}\) hybridization, one s orbital and three p orbitals combine to form four equivalent \(\mathrm{sp}^{3}\) hybrid orbitals.

These hybrid orbitals allow sulfur to form bonds that lead to the molecular geometries predicted by VSEPR, explaining why \(\mathrm{SCl}_{2}\) has its specific arrangement and shape. This hybridization is essential to understand how atoms link to maintain geometrical stability and predict the molecular shape.

valence electrons

Valence electrons are the electrons present in the outermost shell of an atom. They are crucial for understanding how atoms bond in molecules. For sulfur dichloride (\(\mathrm{SCl}_{2}\)), counting valence electrons is the first step in predicting its structure.

• Sulfur, as a Group 16 element, has 6 valence electrons.
• Chlorine, a Group 17 element, has 7 valence electrons.
• With two chlorine atoms, the total count becomes 20 valence electrons as shown by the equation: \(6 + 2 \times 7 = 20\).

Valence electrons are utilized to form bonds between atoms and are represented in the molecule's Lewis structure. They determine the number of bonds an atom can form, affecting the molecule's shape and hybridization. Understanding valence electrons is key for visualizing the initial structure and from there, predicting molecular geometry and hybridization.