Question

Describe the hybridization state of arsenic in arsenic pentafluoride \(\left(\mathrm{AsF}_{5}\right)\)

Short answer

Arsenic in \\(\mathrm{AsF}_{5}\\) is \\(\mathrm{sp}^3\mathrm{d}\\) hybridized.

Step-by-step solution

Understanding the Problem

In this exercise, we need to determine the hybridization state of arsenic in arsenic pentafluoride \((\mathrm{AsF}_{5})\). Hybridization is a concept that explains the molecular geometry and bonding of a molecule by mixing atomic orbitals.

Determine the Valence Electrons

Arsenic is in Group 15 of the periodic table, which means it has 5 valence electrons. Each fluorine atom, being in Group 17, contributes one electron through bonding.

Assess Molecular Geometry

Arsenic pentafluoride \(\mathrm{AsF}_{5}\) forms a trigonal bipyramidal shape, a molecular geometry typical for molecules with five electron groups around the central atom.

Identify the Hybridization

In a trigonal bipyramidal shape, the central atom uses \(\mathrm{sp}^3\mathrm{d}\) hybridization. The combination of one \(\mathrm{s}\), three \(\mathrm{p}\), and one \(\mathrm{d}\) orbital allows for five equivalent orbitals to accommodate the electrons from the five \(\mathrm{F}\) atoms.

Key concepts

Arsenic Pentafluoride

Arsenic pentafluoride, represented as \( \mathrm{AsF}_{5} \), is a chemical compound composed of one arsenic atom and five fluorine atoms. In forming this compound, arsenic serves as the central atom, surrounded symmetrically by the fluorine atoms.
Arsenic pentafluoride is significant in the study of hybridization because it serves as a classic example of \( \mathrm{sp}^3\mathrm{d} \) hybridization, helping to illustrate how atomic orbitals can rearrange themselves to form bonds in molecules with more than typical numbers of electron regions. This molecule is also notable for its role in producing a specific molecular geometry known as trigonal bipyramidal. Understanding the structure of \( \mathrm{AsF}_{5} \) provides insight into how larger molecules with complex shapes are formed.

Valence Electrons

Valence electrons are the outermost electrons of an atom that are used in forming chemical bonds. These electrons determine an atom's chemical properties and reactivity. For arsenic, which belongs to Group 15 of the periodic table, there are five valence electrons available.
In \( \mathrm{AsF}_{5} \), these valence electrons are crucial for bonding. Each fluorine atom, coming from Group 17, contributes one electron to the bond. The presence of paired electrons in overlapping orbitals establishes stable covalent bonds between arsenic and fluorine atoms.
This sharing of electrons leads to a filled outer shell for both the central arsenic atom and the surrounding fluorine atoms, resulting in a stable compound.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It affects the molecule's properties, including polarity, reactivity, and further interaction with other molecules. Geometry provides an understanding of the spatial distribution of the atoms, which is influenced by the number of bonds and lone pairs around the central atom.
In arsenic pentafluoride \( (\mathrm{AsF}_{5}) \), the geometry is organized around five fluorine atoms bonded to the central arsenic. The shape reflects how these atoms arrange to minimize repulsion between electron pairs, leading to stable structures. Identifying the geometry of a molecule is integral to predicting its behavior in chemical reactions and interactions.

Trigonal Bipyramidal Shape

The trigonal bipyramidal shape is a distinct molecular geometry that occurs typically when a molecule has five electron groups around a central atom. This shape consists of three atoms forming a plane in a triangle and two additional atoms that are above and below this plane.
For arsenic pentafluoride, \( \mathrm{AsF}_{5} \), the trigonal bipyramidal shape results from the central arsenic atom forming five bonds with fluorine atoms. This configuration is achieved through a specific type of hybridization, sp\(^3\)d, which uses one \( s \), three \( p \), and one \( d \) orbital.
Understanding this shape is crucial for predicting how the molecule interacts with others, as it impacts polarity and physical properties like boiling and melting points.