Understanding Hybridisation Of ClF₃: Chlorine Trifluoride

Chlorine Trifluoride (ClF₃) has one chlorine and three fluorine atoms. It is an interhalogen compound and undergoes sp³d hybridisation, attaining a T-shaped molecular structure.

Let us understand how hybridisation happens in ClF₃. Read on to learn how it leads to its bonding and molecular shape.

What is the Hybridisation of ClF₃?

Chlorine Trifluoride consists of one central chlorine atom, which is bonded to fluorine atoms and has two lone pairs left. Since chlorine has 5 sets of electrons (3 bonding pairs + 2 lone pairs), it undergoes sp³d hybridisation and follows the principle of expanded octet.

Using the Hybridisation Formula

We can determine the hybridisation of chlorine trifluoride using the simple formula:

formula

Step-by-step calculation:

Valence electrons of central atom (Cl): 7
Monovalent atoms (F): 3 (each fluorine is monovalent)
Negative charge: 0
Positive charge: 0

formula

Interpretation:

Hybridisation number = 5, which corresponds to sp³d hybridisation.

Breakdown of ClF₃ Hybridisation

ClF₃ has a trigonal bipyramidal electron geometry, but it acquires a T-shaped structure. The lone pairs take up equatorial positions, which results in greater repulsion.

Here is a complete understanding of its hybridisation.

Electronic Configuration of Chlorine

The atomic number of chlorine is 17.

The ground state of chlorine:

1s² 2s² 2p⁶ 3s² 3p⁵

Only has one unpaired electron → insufficient to form 3 bonds

Excited state configuration:

1s² 2s² 2p⁶ 3s² 3p⁴ 3d¹

Now, three unpaired electrons → enough to form 3 Cl–F bonds

Also includes lone pairs → total of 5 regions of electron density

Ground state vs excited state orbital diagram of Cl

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 Chlorine Trifluoride

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

Result:

The molecule adopts a T-shape in order to minimise lone pair repulsion.
Hybridisation type: sp³d
Bond angle: 175° and ~87.5° ( due to lone pair repulsion)
Geometry: T-shaped

Geometry and bonding of Chlorine Trifluoride

Details At A Glance

Property	Details
Molecule	Chlorine Trifluoride (ClF₃)
Hybridisation	sp³d
Geometry	T-shaped
Bond angle	175° and ~87.5°
Bonding	3 σ bonds (Cl–F), 2 lone pairs
Unhybridised Orbitals	d-orbitals are involved
Chlorine valency satisfied?	Yes, expanded octet with 10 electrons around Cl
Boiling Point	11.75 °C
Melting Point	−76.34 °C

Formal Charge in ClF₃

To determine if the Lewis structure of ClF₃ 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:

Chlorine (Cl) :

Valence electrons: 7
Lone pairs: 2 (4 electrons)
Bonding electrons: 3
(3 Cl–F bonds with 2 shared electrons each)

Formal charge = 7 – (4 + ½×6) = 7 – (4 + 3) = 0

Fluorine (F) – each

Valence electrons: 7
Lone pairs: 3 (6 electrons)
Bonding electrons: 2

Formal charge = 7 – (6 + 1) = 0

Thus, all atoms in ClF₃ carry zero formal charge, which confirms that the Lewis structure is stable and correct.

Summing Up

Chlorine in ClF₃ forms 3 σ bonds, and ends up with 2 lone pairs. The molecule follows the concept of an expanded octet and thus ends up undergoing sp³d hybridisation. ClF₃ has T-shaped molecular geometry and bond angles of 175° and ~87.5° (due to lone pair repulsion).

Frequently Asked Questions

Q1. Why does chlorine undergo hybridisation in ClF₃?

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

Q2. How many σ and π bonds are present in ClF₃?

There are 3 σ bonds and 0 π bonds in total.

Q3. What is the shape of Chlorine Trifluoride?

T-shaped, due to 3 bonding pairs and 2 lone pairs.

Q4. Is ClF₃ polar or non-polar?

Polar, because the T-shape of ClF₃ causes an uneven distribution of charge.

Q5. What are some uses of Chlorine Trifluoride in our daily lives?

ClF₃ is highly reactive. It is advised to be handled with care and is used for nuclear fuel processing and rocket propellants. Chlorine Trifluoride is also used as a fluorinating agent.