Question

Which of the following statement is false? (1) Octahedral molccular shape exists in sp \(^{3} \mathrm{~d}^{2}\) hybridisation. (2) \(\mathrm{XcF}_{2}\) involves \(\$ \mathrm{p}^{3} \mathrm{~d}\) hybridisation. (3) The repulsion among four hybrid orbitals is smallest if they point to the corners of a square. (4) IIybridisation can take place only between orbitals of roughly the same energy.

Short answer

The false statement is (3).

Step-by-step solution

Analyze Each Statement

Review each statement one by one to determine its validity.

Check Octahedral Molecular Shape

Octahedral molecular shape is associated with \( \mathrm{sp}^{3} \mathrm{~d}^{2} \) hybridization. This statement is true.

Verify \( \mathrm{XeF}_{2} \) Hybridization

\( \mathrm{XeF}_{2} \) has a linear structure involving \( \mathrm{sp}^{3} \mathrm{~d} \) hybridization, which makes this statement true as well.

Analyze Repulsions Among Hybrid Orbitals

Among the four hybrid orbitals, the repulsion is smallest if they point to the corners of a tetrahedron, not a square. So, this statement is false.

Hybridization Energy Levels

Hybridization generally occurs among orbitals of similar energy levels. Therefore, this statement is true.

Key concepts

sp3d hybridization

Let's start with understanding the concept of sp3d hybridization. In chemical bonding, hybridization refers to the mixing of atomic orbitals to form new hybrid orbitals. These hybrid orbitals are crucial for explaining the shape of molecules.
For sp3d hybridization, one s-orbital, three p-orbitals, and one d-orbital mix together to form five equivalent hybrid orbitals. These hybrid orbitals arrange themselves in a specific geometry to reduce electron repulsion. This typically results in a trigonal bipyramidal shape.
An example of sp3d hybridization can be seen in molecules like phosphorus pentachloride (PCl5). Here, the geometry results from the arrangement of three equatorial atoms making a triangle and two axial atoms located above and below the plane of the equatorial atoms. This helps in minimizing repulsion and stabilizing the molecule.

octahedral molecular shape

The octahedral molecular shape is linked to sp3d2 hybridization, which involves six hybrid orbitals. These orbitals are formed by the mixing of one s-orbital, three p-orbitals, and two d-orbitals. They arrange themselves in such a way as to minimize electron repulsion.
Picture an octahedron: a three-dimensional shape with eight faces. In an octahedral molecule, six atoms or groups are positioned symmetrically around a central atom, at the corners of an octahedron.
A common example of octahedral molecular shape is sulfur hexafluoride (SF6). Here, six fluorine atoms are symmetrically arranged around a central sulfur atom. This arrangement allows for minimal repulsion between the atoms, leading to a highly stable structure.

orbital repulsion

Orbital repulsion is a fundamental concept in chemistry. It refers to the repelling force between electron pairs within orbitals. As negative charges repel each other, electron pairs tend to arrange themselves as far apart as possible to reduce repulsion.
This concept is essential in determining the shape of molecules. For example, in the case of tetrahedral geometry, the four hybrid orbitals point to the corners of a tetrahedron to minimize repulsion. The statement mentioned that repulsion is smallest if the orbitals point to the corners of a square is inaccurate. In reality, a tetrahedral arrangement minimizes repulsion better than a square.
Understanding orbital repulsion helps us accurately predict molecular shapes using Valence Shell Electron Pair Repulsion (VSEPR) theory. By considering the repulsions between bonding and non-bonding electron pairs, chemists can determine the most stable structure for a molecule.