Understanding Hybridisation of XeF₂: Xenon Difluoride

Xenon Difluoride (XeF₂) is also known as Difluoroxenon. It has one xenon atom bonded to two fluorine atoms. It’s an excellent example of sp³d hybridisation in inorganic chemistry.

Let us understand how hybridisation happens in XeF₂. Read on to learn how it leads to its bonding and molecular shape.

What is the Hybridisation of XeF₂?

Xenon Difluoride consists of one central xenon atom (a noble gas), which is bonded to fluorine atoms and has three lone pairs left. Since xenon has 5 regions of electron density (2 bonding pairs + 3 lone pairs), it undergoes sp³d 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 difluoride using a simple formula:

Step-by-step calculation:

Valence electrons of xenon (Xe) = 8
Monovalent atoms (fluorine = 2) = 2
Negative charge = 0
Positive charge = 0

formula

Interpretation:

Hybridisation number = 5 → sp³d
Geometry (according to VSEPR) = Trigonal bipyramidal electronic geometry
Actual shape = Linear (since 3 lone pairs occupy the equatorial positions, forcing the 2 fluorine atoms to remain opposite each other)
Bond angle = 180°

Breakdown of XeF₂ Hybridisation

XeF₂ has a trigonal bipyramidal electron geometry, but it acquires a linear molecular geometry. The lone pairs take up equatorial positions, leading the fluorine atoms to take the axial positions. 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 :

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶

In the ground state, xenon has a complete octet (all paired electrons in 5p orbitals), so it normally does not form bonds.

Excited state configuration:

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵ 5d¹

Now, five 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

sp³d hybridisation occurs when 1 s orbital, 3 p orbitals, and 1 d orbital mix to form equivalent hybrid orbitals.
The result:
→ 5 sp³d hybrid orbitals are formed
→ These accommodate lone pairs and are used to form bonds between atoms.

Bond Formation in Xenon Difluoride

The xenon atom uses:

2 sp³d hybrid orbitals overlap with the p orbitals in the fluorine atom and form 2 σ bonds.
The remaining 3 sp³d hybrid orbitals contain lone pairs of electrons.

Result:

The molecule adopts a linear structure in order to minimise lone pair repulsion.
Hybridisation type: sp³d
Bond angle: 180° (F–Xe–F)
Geometry: Linear

Geometry of Xenon Difluoride

Details At A Glance

Property	Details
Molecule	Xenon Difluoride (XeF₂)
Hybridisation	sp³d
Geometry	Linear
Bond angle	180°
Bonding	2 σ bonds (Xe–F), 3 lone pairs
Unhybridised Orbitals	0 (all involved in hybridisation)
Xenon valency satisfied?	Yes, by forming 2 bonds and holding 3 lone pairs

Formal Charge in XeF₂

To determine if the Lewis structure of XeF₂ 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: 3 (6 electrons)
Bonding electrons: 4 (2 Xe–F bonds)

Formal charge = 8 – (6 + ½ × 4) = 8 – (6 + 2) = 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 XeF₂ carry zero formal charge, which confirms that the Lewis structure is stable and correct.

Summing Up

Xenon in XeF₂ forms 2 σ bonds and ends up with 3 lone pairs. The molecule follows the concept of an expanded octet and thus ends up undergoing sp³d hybridisation. XeF₂ has Linear molecular geometry and bond angles of 180° (due to lone pair repulsion).

Frequently Asked Questions

Q1. Why does xenon undergo hybridisation in XeF₂?

To form 2 single bonds with fluorine and also accommodate 3 lone pairs, xenon hybridises into sp³d orbitals.

Q2. How many σ and π bonds are present in XeF₂?

There are 2 σ bonds and 0 π bonds in total.

Q3. What is the shape of Xenon Difluoride?

Linear, due to 2 bonding pairs and 3 lone pairs.

Q4. Is XeF₂ polar or non-polar?

Non-polar, as the molecule has a symmetrical linear shape due to bond dipoles.

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

Xenon Difluoride is used as a fluorinating agent in the process of chemical synthesis. It is also used in semiconductor etching and as a mild oxidising agent.