The ClF molecule has sp3 hybridization on both atoms and is not hypervalent. If chlorine turns into a cationic centre, it keeps its sp3 hybridization and can be able to accept two fluorine atoms. The resonance allows the axial fluorine atoms to be kept in place by chlorine atoms in Chlorine Trifluoride (ClF3).
Let us examine the hybridization of ClF3 and understand how the hybridization occurs actually. Normally, the Chlorine Trifluoride (ClF3) is an sp3d hybridized. Let us look at some properties of ClF3, such as the molecular name, formula, and more.
If we speak about the hybridization of chlorine trifluoride, we should consider its central atom, which is Chlorine (Cl). This atom holds 7 valence electrons while ClF3should consist of 2 lone-pairs and 3 bond-pairs. If we closely notice the valence electronic configuration of Chlorine (Cl), it is represented as 3px2, 3s2, 3py2, 3pz1, 3d.
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Now, when the Cl needs to combine with Fluorine atoms to form ClF3, it requires three unpaired electrons to bond with the three F-atoms. Here, one of the paired electrons of Cl present in the 3p subshell remains as either a lone pair or unpaired. All in all, during the hybridization, one 3s orbital, three 3p orbitals, and one of the 3d orbitals participate in the process that leads to the formation of five sp3d hybrid orbitals. Besides, here the two-hybrid orbitals will contain a pair of electrons, and three hybrids orbitals will contain unpaired electrons, which again will overlap with the 2p orbital of F to form the resultant single bonds.
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Predicting molecular geometry and hybridization of ClF3 can be done using some methods. Chlorine Trifluoride (ClF3) represents a Trigonal bipyramidal geometry. If the central atoms contain 5 bond repulsion units and if it doesn’t contain a lone pair on the central atom, the molecule shape is trigonal bipyramidal having a bond angle of 175° F-Cl-F. If two bonds of the trigonal bipyramidal basic geometry are changed into two lone pairs, therefore hybridization and shape of ClF3 shape will be in “T” shape. There also exists an asymmetric charge distribution around the ClF3 hybridization of the central atom.
Thus, Chlorine Trifluoride (ClF3) has 2 lone pairs and 3 bond repulsion units. Therefore, it is Trigonal bipyramidal, and the bond angle is 90°.
A few of the important points to remember are listed below.
The Chlorine Trifluoride (ClF3) should consist of 2 lone-pairs and 3 bond-pairs.
The central atom, Cl requires three unpaired electrons to bond with three F-atoms.
One 3s, three 3p, and one of the 3d orbitals of Cl participate in the hybridization, and thereby, five sp3d hybrid orbitals are formed.
The equatorial-axial F–Cl–F (taken from the T shaped, based on the Trigonal Bipyramidal) bond angles are less than 90° because of the lone-pair:bonding-pair repulsion with being greater than that of the bonding-pair:bonding-pair repulsion.
The lone pairs occupy the equatorial positions on the trigonal bipyramid. This minimizes the 90° number lone-pair:bonding-pair interactions.
For the same reason, the axial-axial F–Cl–F bond angle is less than 180°.
Let us state the hybridization of cl in ClF3. In the hybridization of chlorine in ClF3, we get 28 electrons, where 14 electron pairs are distributed around the central, least electronegative, chlorine atom, then we get ClF3.
Two lone pairs are associated with the central chlorine atom and therefore form a trigonal bipyramidal electronic geometry. We can describe the molecular geometry in terms of atoms, but not electrons. Thus, ClF3 is T-shaped, having the axial ∠F−Cl−F compressed from the angle of 180°, which is a formal sp3d hybridization.
As it is known that chlorine (Cl) can have more than one valency. The valency of chlorine (Cl) is dependent on the other atoms to which it is bonded. If the other atoms to which chlorine are bonded are more electronegative to that of the chlorine (bonded to oxygen or fluorine), then the chlorine will contain a positive charge. Some common molecules formed with the chlorine along with the charge (valency) on the chlorine are given below.
HCl valency = -1
ClO− valency = +1
ClO2- valency = +3
ClO3- valency = +5
ClO4- valency = +7
By the explanation given above, we can notice that chlorine has more than one valency. It can have the valencies in between -1 and +7 in steps of 2. This is true for also other non-metals. For example, nitrogen can be +5, +3, +1, -1, and -3, and carbon can be +4, +2, 0, -2, and -4.
So, the Chlorine Trifluoride ClF3 (with a valency, +3) is not an unusual compound. Based on the range of possible chlorine valencies, this compound should be expected.
1. Why does Chlorine Exist as Cl2 instead of Cl?
Ans: As Cl2 is more stable than one chlorine atom, Cl holds 7 electrons in its outer shell, means to obtain noble gas configuration (stable) it should gain one more electron. So, there are more chlorine atoms, they will react with each other and can form covalent bonds i.e. a shared pair of electrons between the two atoms.
As the atoms share one electron with the other atom each, they both have 8 electrons in their outer shell; basically, that makes them even more stable.
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Chlorine can live as a single chlorine atom, called a radical. It means that it has an unpaired electron in its outer shell and is so reactive. Usually, radicals like this don't exist for so long as they tend to react more quickly. By an unpaired electron, it has an orbital that is only occupied by one electron.
So, molecules and atoms exist in low energy states and with stable configurations. Cl2 is much more stable than chlorine radicals. So, the atoms will just react with themselves, when there is chlorine because chlorine is very reactive on its own.
2. Why does Chlorine Live as a Diatomic Molecule at Room Temperature?
Ans: There are many reasons why chlorine lives as a diatomic molecule at room temperature. Let us have a look at a few of them.
Because the neutral Cl atom has a high electron affinity and will share the electrons covalently with the other atom.
Because each chlorine (Cl) atom has only one electron to produce a formal bond within the valence shell.
Because although technically empty 3d valence orbitals are there in the 3rd quantum shell, due to the electron repulsion terms, energetically, they are not available for donor-acceptor interactions (can occur at room temperature in the solid-state.