Question

The struture of \(\mathrm{IF}_{7}\) is: (a) Octahedral (b) Trigonal bipyramid (c) Square pyramid (d) Pentagonal bipyramid

Short answer

The structure of \( \mathrm{IF}_7 \) is a pentagonal bipyramid (option d).

Step-by-step solution

Understanding the Molecular Geometry

To find the structure of \( \mathrm{IF}_7 \), we need to consider the arrangement of iodine and fluorine atoms in the compound. \( \mathrm{IF}_7 \) contains one iodine atom surrounded by seven fluorine atoms.

Determining Electron Geometry

Iodine in \( \mathrm{IF}_7 \) undergoes sp\(^3\)d\(^3\) hybridization because it forms seven bonds using 5 valence electrons and pairs them with 7 fluorine atoms. This hybridization is typical for a 7-coordination geometry.

Identifying the Geometrical Shape

For molecules with sp\(^3\)d\(^3\) hybridization such as \( \mathrm{IF}_7 \), the theoretical shape is a pentagonal bipyramid. This is due to the symmetry and arrangement of electrons that minimize the repulsion forces according to the VSEPR theory.

Matching with Options

From the given options, (a) Octahedral, (b) Trigonal bipyramid, (c) Square pyramid, and (d) Pentagonal bipyramid, the correct geometry corresponding to \( \mathrm{IF}_7 \) is a pentagonal bipyramid, matching option (d).

Key concepts

VSEPR Theory

The Valence Shell Electron Pair Repulsion (VSEPR) theory is a fundamental concept in chemistry used to predict the geometry of individual molecules. It helps us understand how the shape of a molecule is determined by the repulsion between electron pairs surrounding a central atom.

According to this theory, electron pairs, including bonding and lone pairs, will arrange themselves as far apart as possible around the central atom to minimize repulsive forces. This arrangement affects the overall shape of the molecule.

• The number of bonded electron pairs and lone pairs around the central atom determines the molecule's geometry.
• For instance, with seven bonded pairs and zero lone pairs, molecules tend to form a pentagonal bipyramid, as is the case with IF₇.

This explains why iodine fluoride compounds like IF₇ exhibit a specific shape that adheres to the principles of the VSEPR theory.

sp3d3 Hybridization

Hybridization is a concept that explains how atomic orbitals within an atom mix together to form new hybrid orbitals. These hybrid orbitals are used to bond with other atoms in a molecule.

In the molecule IF₇, iodine undergoes sp³d³ hybridization. This process involves the mixing of one s orbital, three p orbitals, and three d orbitals to create seven equivalent hybrid orbitals. Each of these hybrid orbitals can form a bond with a fluorine atom.

This type of hybridization is crucial for molecules with seven bonds, enabling them to adopt a geometry consistent with the spatial arrangement of the atoms. It's essential to understand that hybridization helps to predict how atoms will bond and the resulting geometry of molecules.

Iodine Fluoride Compounds

Iodine fluoride compounds, such as IF₇, are fascinating due to their diverse bonding configurations and geometries. These compounds involve iodine covalently bonded to multiple fluorine atoms, creating unique shapes.

For IF₇, the molecule is characterized by seven fluorine atoms surrounding a central iodine atom, forming a pentagonal bipyramidal structure. This specific geometry is due to the bonding pattern allowed by the involvement of the d orbitals in hybridization.

• The high number of fluorine atoms around iodine leads to coordination configurations that are uncommon in smaller molecules.
• The presence of multiple bonds contributes to the molecule's stability and influences its physical and chemical properties.

Understanding the arrangement in iodine fluoride compounds helps predict reactivity and interaction patterns with other substances.