Question

Which statement is wrong? (1) IIybridisation is the mixing of atomic orbitals prior to thcir combining into molecular orbitals. (2) sp \(^{2}\) hybrid orbitals are formed from two \(\mathrm{p}\) - and one s-atomic orbitals. (3) sp \(^{3} \mathrm{~d}\) hybrid orbitals are all at \(90^{\circ}\) to one another. (4) \(\mathrm{sp}^{3} \mathrm{~d}^{2}\) hybrid orbitals are directed towards the corners of the regular octahedron.

Short answer

Statement (3) is wrong.

Step-by-step solution

Understand Hybridisation

Hybridisation is the mixing of atomic orbitals to form new hybrid orbitals. These hybrid orbitals have different shapes and energies than the original atomic orbitals. Statement (1) is correct as it describes the concept of hybridisation.

Analyze sp² Hybrid Orbitals

sp² hybrid orbitals are created from one s-orbital and two p-orbitals. This combination forms three hybrid orbitals. Statement (2) is accurate as it correctly defines the formation of sp² hybrid orbitals.

Check Geometry of sp³d Orbitals

sp³d hybrid orbitals are formed from one s-orbital, three p-orbitals, and one d-orbital. These orbitals create a trigonal bipyramidal geometry, where the angles are not all 90°. Statement (3) is incorrect because it states that all sp³d orbitals are at 90° angles to each other.

Evaluate sp³d² Hybrid Orbitals

sp³d² hybrid orbitals are formed from one s-orbital, three p-orbitals, and two d-orbitals. These form an octahedral geometry, with orbitals directed towards the corners of a regular octahedron. Statement (4) is correct as it matches the description of sp³d² hybrid orbitals.

Key concepts

sp2 hybrid orbitals

When we talk about sp² hybrid orbitals, we are referring to a specific type of hybridisation. During sp² hybridisation, one s-orbital and two p-orbitals from an atom's electron cloud mix together.
This mixing results in three new, identical hybrid orbitals. These orbitals are called sp² because they are composed of one s-orbital and two (p²) p-orbitals.
What makes sp² hybridisation unique are the shapes and geometries that these hybrid orbitals form.

• sp² hybrid orbitals arrange themselves in a trigonal planar structure.
• This structure means that the orbitals are spread out at 120° angles from each other.
• Think of this arrangement like the points of an equilateral triangle.

In simpler terms, imagine you are looking down at the top of a triangle. The three corners of this triangle represent the positions of the sp² hybrid orbitals.
This structure is essential in understanding the behavior of molecules in organic chemistry, particularly ones involving double bonds, like in alkenes.

sp3d hybrid orbitals

Let's delve into sp³d hybridisation, a more complex form of orbital mixing. In sp³d hybridisation, we combine one s-orbital, three p-orbitals, and one d-orbital from the same atom.
This combination forms five new hybrid orbitals, called sp³d hybrid orbitals.
The geometry of these sp³d hybrid orbitals is trigonal bipyramidal. Here's what this means:

• This geometry consists of a triangular plane with three hybrid orbitals at 120° angles to each other.
• There are also two more hybrid orbitals that are 90° above and below this plane.

It's important to note that not all angles between these orbitals are 90° during sp³d hybridisation.
This is because the trigonal bipyramidal geometry has different bonding angles. Thus, statement (3) in the exercise is incorrect.
Visualize the structure as a triangular base with a vertical bond coming out from the top and bottom. This layout is significant in many advanced chemistry applications.

octahedral geometry

Octahedral geometry is associated with sp³d² hybridisation. This type of hybridisation involves the mixing of one s-orbital, three p-orbitals, and two d-orbitals.
When these orbitals hybridize, they form six identical hybrid orbitals. These are called sp³d² hybrid orbitals.
The resulting geometry is known as octahedral because it forms a shape with eight faces, much like an octahedron.

• All six sp³d² hybrid orbitals are directed towards the corners of an octahedron.
• In simpler terms, visualize a square base with four corners, and an additional point sticking out both above and below the square.
• This layout creates six positions or corners in the three-dimensional space.

All bond angles in an octahedral geometry are 90°, providing a symmetrical and stable configuration.
This type of hybridisation is common in coordination complexes and other molecules where an atom is bonded to six ligands.