Question

Solid \(\mathrm{PCl}_{5}\) exists as \(\left[\mathrm{PCl}_{4}^{+}\right]\left[\mathrm{PCl}_{6}^{-}\right]\). Draw Lewis structures for these ions. Describe the hybridization state of the \(\mathrm{P}\) atoms

Short answer

\([PCl_4^+]\) has \(sp^3\) hybridization; \([PCl_6^-]\) has \(sp^3d^2\) hybridization.

Step-by-step solution

Understanding the Problem

The compound \[\text{PCl}_{5}\]exists as the ions \[\left[\text{PCl}_{4}^{+}\right]\]and \[\left[\text{PCl}_{6}^{-}\right]\]. Our task is to draw the Lewis structures for these ions and describe the hybridization state of the phosphorus (\(\text{P}\)) atoms.

Draw Lewis Structure for \([PCl_4^+]\)

In the ion \[[PCl_4^+]\], the phosphorus atom bonds with four chlorine atoms. The phosphorus atom donates one of its electrons, resulting in a positive charge, leading to the electron configuration of \[4\] valence electrons. - Arrange the chlorine atoms around the central phosphorus atom. - Form single bonds between phosphorus and each chlorine. - Each chlorine atom reaches an octet configuration, leaving phosphorus with a \[sn\]configuration. Therefore, there are \[4\] single bonds surrounding P, with one positive charge remaining on phosphorus.

Determine Hybridization of \([PCl_4^+]\)

The hybridization can be determined by the number of bonded atoms and lone pairs around \(\text{P}\).- P has four bonded atoms and no lone pairs in \[[PCl_4^+]\].- Use the formula: \[sp^n,\ n = \text{(number of bonded atoms + lone pairs)}\]. Since it's \[4\], P has \[sp^3\] hybridization.

Draw Lewis Structure for \([PCl_6^-]\)

In the ion \[[PCl_6^-]\], the phosphorus atom bonds with six chlorine atoms. - Arrange the six chlorine atoms around the central phosphorus atom. - Form single bonds between phosphorus and each chlorine atom. - This allows each chlorine atom to complete its octet, and phosphorus accepts an extra electron, giving it a negative charge, \[\text{P}Cl_6^-\].

Determine Hybridization of \([PCl_6^-]\)

The hybridization of \(\text{P}\) in \([\text{PCl}_6^-\) is determined by bonded atoms and lone pairs. - P has six bonded atoms and no lone pairs. - Using formula: \[sp^n, \ n = \text{(number of bonded atoms + lone pairs)}\], here it is \[6\]. - Thus, P has \[sp^3d^2\] hybridization.

Key concepts

Understanding Hybridization

Hybridization is a key concept in chemistry that describes how atomic orbitals mix to form new, hybrid orbitals. These hybrid orbitals are responsible for the geometry and bonding properties of molecules.
For example, carbon in methane ( CH_4 ) undergoes sp^3 hybridization to form four equivalent bonds. In essence, hybridization helps explain the structure of molecules in three-dimensional space.

Exploring the PCl4+ Ion

The PCl4^+ ion is an interesting example of molecular geometry. In this ion, a phosphorus atom is at the center, bonded to four chlorine atoms. The central phosphorus donates one electron, creating a positive charge.
The resulting electron configuration also means phosphorus has four valence electrons available for bonding, leading to a tetrahedral shape for the ion. Understanding the electron arrangement helps us determine the ion's hybridization.

Investigating the PCl6- Ion

The PCl6^- ion is characterized by its unique shape. The central phosphorus atom forms bonds with six chlorine atoms. Unlike the PCl4^+ ion, phosphorus accepts an additional electron here, resulting in a negative charge.
This negative charge affects the electron distribution and contributes to the ion's octahedral geometry. The ion's structure and electron count are crucial to understanding its hybridization state.

Role of the Phosphorus Atom

Phosphorus atoms in these ions showcase how versatile this element can be in bonding scenarios. In PCl4^+ and PCl6^- , phosphorus displays different hybridization states.
In PCl4^+ , phosphorus is involved in sp^3 hybridization, forming four equivalent sp^3 orbitals, while in PCl6^- , it undergoes sp^3d^2 hybridization, indicating the presence of six equivalent orbitals. This adaptability highlights phosphorus's ability to accommodate different numbers of bonded atoms around it.