Understanding Hybridisation of XeF₄: Xenon Tetrafluoride

Xenon Tetrafluoride (XeF₄) is also known as Xenon(IV) fluoride. It has one xenon atom bonded to four fluorine atoms. Its square planar geometry is unusual. It’s an excellent example of sp³d² hybridisation in inorganic chemistry.

Let us understand how hybridisation happens in XeF₄. Read on to learn how it leads to its bonding and molecular shape.

What is the Hybridisation of XeF₄?

Xenon tetrafluoride consists of one central xenon atom, which is bonded to fluorine atoms and has two lone pairs left. Since xenon has 6 sets of electrons (4 bonding pairs + 2 lone pairs), it undergoes sp³d² hybridisation and follows the principle of expanded octet (as d orbitals are available in the valence shell).

Using the Hybridisation Formula

We can determine the hybridisation of xenon tetrafluoride using a simple formula:

Step-by-step calculation:

Valence electrons on Xe = 8
Number of monovalent atoms (F) = 4
Negative charge = 0
Positive charge = 0

formula

Interpretation:

Hybridisation: sp³d²
Electron-pair geometry (VSEPR): Octahedral (6 regions of electron density)
Molecular shape: Square planar (two lone pairs occupy positions opposite each other, leaving four F atoms in one plane)
Bond angles: 90° and 180°
Key point: The trans arrangement of lone pairs minimises lone-pair–lone-pair repulsion, yielding the square-planar shape.

Breakdown of XeF₄ Hybridisation

XeF₄ has an octahedral electron geometry, but it acquires a square planar molecular geometry. The lone pairs take up axial positions, since they would minimise repulsion. The VSEPR Theory explains all this.

Here is a complete understanding of its hybridisation.

Electronic Configuration of Xenon

The atomic number of xenon is 54.

The ground state of xenon :

formula

Does not have unpaired electron → insufficient to form four bonds

Excited state configuration:

formula

Now, four unpaired electrons → enough to form bonds and still have space for lone pair of electrons.

Ground state vs excited state orbital diagram

Formation of Hybrid Orbitals

sp³d² hybridisation occurs when 1 s orbital, 3 p orbitals, and 2 d orbitals mix to form equivalent hybrid orbitals.
The result:
→ 6 sp³d² hybrid orbitals are formed
→ These accommodate lone pairs and are used to form bonds between atoms.

Bond Formation in Xenon Tetrafluoride

The xenon atom uses:

4 sp³d² hybrid orbitals overlap with the p orbitals in the fluorine atom and form 4 σ bonds.
The remaining 2 sp³d² hybrid orbitals contain lone pairs of electrons.

Result:

4 Xe–F σ bonds
2 Lone Pairs
The molecule adopts a square planar structure in order to minimise lone pair repulsion.
Hybridisation type: sp³d²
Bond angle: 180° and 90°
Geometry: Square planar

Geometry of Xenon Tetrafluoride

Details At A Glance

Property	Details
Molecule	Xenon Tetrafluoride (XeF₄)
Hybridisation	sp³d²
Geometry	Square planar
Bond angle	90°, 180°
Bonding	4 σ bonds (Xe–F), 2 lone pairs, 0 π bonds
Unhybridised Orbitals	0 (all involved in hybridisation)
Xenon valency satisfied?	Yes, by forming 4 bonds and holding 2 lone pairs

Formal Charge in XeF₄

To determine if the Lewis structure of XeF₄ is stable, we calculate the formal charge on each atom using the formula:

Formal charge = Valence electrons – (Lone pair electrons + ½ × Bonding electrons)

Step-by-step for each atom:

Xenon (Xe):

Valence electrons: 8
Lone pairs: 2 (4 electrons)
Bonding electrons: 8 (4 Xe–F bonds)

Formal charge = 8 – (4 + ½×8) = 8 – (4 + 4) = 8 – (8) = 0

Fluorine (F) – each

Valence electrons: 7
Lone pairs: 3 (6 electrons)
Bonding electrons: 2 (1 single bond with Xe)

Formal charge = 7 – (6 + ½×2) = 7 – (6 + 1) = 7 – (7) = 0

Thus, all atoms in XeF₄ molecule carry zero formal charge, which in turn concludes and confirms that the Lewis structure is stable and correct.

Summing Up

Xenon in XeF₄ forms 4 σ bonds and ends up with 2 lone pairs. The molecule follows the concept of an expanded octet and thus ends up undergoing sp³d² hybridisation. XeF₄ has square planar molecular geometry (with octahedral electron pair geometry).

Frequently Asked Questions

Q1. Why does xenon undergo hybridisation in XeF₄?

To form 4 single bonds with fluorine and also accommodate 2 lone pairs, xenon hybridises into sp³d² orbitals.

Q2. How many σ and π bonds are present in XeF₄?

There are 4 σ bonds and 0 π bonds in total.

Q3. What is the shape of Xenon Tetrafluoride?

Square planar, due to 4 bonding pairs and 2 lone pairs.

Q4. Is XeF₄ polar or non-polar?

Non-polar, as the bond dipoles cancel out since it has square planar molecular geometry.

Q5. What are some uses of Xenon Tetrafluoride in our daily lives?

Xenon Tetrafluoride is used as a fluorinating agent in the process of chemical synthesis. It is also used in etching semiconductors in microelectronics.