Chlorine trifluoride or ClF3 is an extremely reactive chemical compound with several varied applications and unique physical and chemical compounds.
An interhalogen compound having both Cl and F, it has a density of around 3.79 g/l and a molar mass of 92.45 g/mol.
ClF3 exhibits a strong suffocating pungent odor and varies from colorless gaseous to green liquid form.
ClF3 is a powerful fluorinating agent and also acts as a strong oxidizer.
This makes this compound a suitable choice in propellants and nuclear reactors or as incendiary. It is also used for plasma-less cleaning in semiconductors and for reprocessing of reactor fuels.
However, it is a highly poisonous and corrosive gas and proves to be fatal when inhaled. Also, it can cause excessive damage to skin, eyes and therefore highly toxic. It can lead to uncalled-for explosions.
Do you know that when ClF3 participates in a hydrolysis reaction, it often turns violent?
So, it is really important to take good care and safety precautions while handling the chemical to avoid any form of hazards.
ClF3 Lewis Structure
Calculate the total number of Valence Electrons
Let us first understand the concept of valence electrons and the octet rule.
Valence electrons signify the number of electrons present around atomic nuclei in the outermost shell, also known as the valence shells.
If we look at the periodic table, we can easily find out the number of valence electrons present in each atomic element in its ground state from the atomic number. This denotes valency.
The main group elements have a tendency or an inherent inclination towards octet fulfillment which simply signifies that they intend to have eight valence electrons like the noble gas configurations of the same period.
For example, Carbon (atomic no:6) has a tendency to have an octet configuration as neon ( atomic no:10 and the noble gas of the same period)
Now, we will calculate the valence electrons in ClF3:
ClF3 has one chlorine atom and three fluorine atoms. Chlorine has an atomic number of 17 and Fluorine has an atomic number of 9.
Both of them belong to group 7 of the periodic table and have a valency of 7.
Total number of valence electrons in ClF3 = 7 + 7*3 = 28.
Find out the Central Atom in the Molecule
How can we find out the central atom inside a multiatomic heterogeneous molecule?
For this, we need to recapitulate the theory of electronegativity.
An atomic element always tends to attract negatively charged electrons. This chemical property is known as electronegativity and varies across the lengths and breadths of the periodic table.
Now, the element which is supposedly the least electronegative among all the elements constituting a molecule is considered to be the central atom.
Here, therefore, the chlorine is taken to be the central atom.
Draw the Skeletal Diagram of the molecule
We will draw the skeletal sketch of the molecule with the help of the atomic symbols and valence electrons via electron dot structure.
Check Octet Fulfillment
We have already discussed the octet fulfillment rule. This is done to keep the outer shell electrons satisfied. So, we will place the electrons around atoms to fulfill the octet configurations.
Let us look at this sketch below:
Note: The total number of electrons in the diagram is 26 and not 28.
We will draw the bonds in the molecule. But before that, we will complete the valence electron count to 28.
Sharing of a pair of electrons leads to the single bond formation, hence the diagram will be:
We can see the three single bonds formed: Cl-F
Check the Formal Charge
We are never really sure whether we have got our perfect Lewis structure. Therefore, here comes the concept of a formal charge.
Definition: When we assign a charge to any bonded atom, it is assumed that the charge is shared equally among all the bonded atoms. This is known as a formal charge.
This is how we find out formal charge:
We will now check whether all the bonded atoms in chlorine trifluoride are in their least or minimum possible formal charges.
Formal charge of Cl = Valence electrons (7) – 0.5*Bonding electrons (6) – Lone pair of electrons (2*2)
= 7 – 3 – 4 = 0.
Formal charge of each F atom = Valence electrons (7) – 0.5*Bonding electrons (2) – Lone pair of electrons ( 2*3)
= 7 – 1 – 6 = 0.
Therefore, we have got the most perfect Lewis Structure of ClF3.
Now, we can move on to our next topic.
ClF3 Molecular Geometry
We have already drawn the 2-dimensional Lewis Structure of ClF3. Our next task is to decipher the 3-dimensional geometry of the given molecule.
This is known as molecular geometry.
VSEPR stands for Valence Shell Electron Pair Repulsion model theory. This is the most commonly used theoretical basis on which people of chemistry love to predict the molecular shape of a molecule.
Electrons are negatively charged subatomic particles that form a likely charged cloud around nuclei that tend to cause repulsion.
Hence, to get a balanced molecular structural composition, this electron repulsion needs to be minimized as much as possible. VSEPR model is based on this fact.
ClF3 Molecular Shape
Here, we have to find out the perfect molecular geometrical shape of ClF3.
Let’s look at this VSEPR chart.
We can see that we need to find out the number of lone pairs and the steric number of the central atom to calculate the molecular geometry.
We already know about the lone pair or non-bonded electron pair concept. In ClF3, we have 2 lone pairs over central chlorine, an exception to the octet rule.
A molecule can be at its most stable state when its energy has been in its lowest form, therefore the electron repulsion has been minimized.
The steric number is a noteworthy terminology used in VSEPR theory. It refers to the number of domains connected or attached to the central atom.
Steric number in ClF3 = 3 ( No. of bonded electrons) + 2 ( Lone pair) = 5
Now, have a look at the above chart again.
The VSEPR theory suggests that the molecular shape of ClF3 is T- shaped.
What is Orbital Hybridization?
Orbital hybridization is an essential concept of chemical bonding that we cannot skip. We all know that there are several atomic orbitals: s, p, d, and f.
AOs are mainly the probable regions or spaces inside an atom around the nuclei where we can expect the presence of electrons and these atomic orbitals vary in shape, abundance, and size.
Hybridization is the process of fusion and mixing of atomic orbitals of different types to result in hybridized orbitals.
Type of hybridization in ClF3
Cl: 1s2 2s2 2p6 3s2 3p5
F: 1s2 2s2 2p5
In chlorine, we have for the valence 3 shell, filled s, px, py filled, pz half-filled, and empty d orbitals.
The paired electrons will shift towards d orbitals and the hybridization will take place via one s, the three p, and one d orbital.
We have therefore sp3d hybridization.
Polarity is another subject on chemical bonding that we need to learn about. So, how to know whether a molecule is polar or non-polar?
Do you know that it is just our assumption that electrons will be shared in equal proportion while a bond is getting formed? The fact is, it is not!
The atomic elements possess partial charges( positive and negative) while forming any bond and the distance in the bond is created which helps in measuring dipole moment.
If the charges cancel each other( for example, always in the case of homogeneous diatomic molecules), then there is no net dipole which results in non-polarity.
If there is an electronegativity difference, then the molecule has a net dipole. The said molecule is polar in nature.
If we look at the Pauling scale, we can find out the values of electronegativity of periodic table elements. A chlorine atom has an electronegativity of 3.16 whereas a fluorine atom, being highly electronegative has a value of 3.98.
So here, the partial positive charge is being held by Cl, and the partial negative charge is being held by F atoms in each Cl-F bond inside chlorine trifluoride.
Therefore, due to the high difference in electronegativity, there is a net dipole which results in polarity.
ClF3 is a polar molecule.
In this article, we have discussed the chemical bonding of chlorine trifluoride.
We have tackled the Lewis structure, hybridization, molecular geometry, and polarity. Hope you have been benefitted from this detailed explanation.