ClF3 lewis structure comprises three fluorine (F) atoms and one chlorine (Cl) atom. The chlorine (Cl) atom is kept at the central position and the fluorine (F) atoms are in the surrounding position in the lewis diagram. The lewis dot structure of ClF3 contains total of 11 lone pairs and 3 bond pairs.
Follow these steps to draw the stable ClF3 Lewis dot structure.
1. Count total valence electrons in ClF3
In the first step, count all valence electrons present in this molecule. Both chlorine and fluorine belong to the 17th group in the periodic table.
- Valence electrons in chlorine = 7
- Fluorine valence electrons = 7
∴ Total valence electrons available for drawing the ClF3 lewis structure = 7 + 7*3 = 28 valence electrons.
2. Find the least electronegative atom
Both chlorine and fluorine belong to the same group in the periodic table. And we need to find which atom has less electronegativity.
Fluorine is the most electronegative element in chemistry, so, it always goes outside in the lewis diagram.
Place the chlorine atom at the center in the lewis diagram and fluorine atoms spaced evenly around it.
3. Connect outer atoms with the central atom
In this step, we need to connect every outer atom to the central atom with the help of a single bond.
As you see in this structure, we used three single bonds to connect each outer atom to the central atom. So, we used 6 electrons from a total of 28 valence electrons.
∴ (28 – 6) = 22 valence electrons
Now we are left with 22 valence electrons.
4. Complete the octet of outer atoms
The F atoms are the outer atoms in the ClF3. Each F atom requires a total of 8 valence electrons in order to achieve a stable octet electronic configuration.
There are three Cl-F bonds in the ClF3Lewis diagram drawn till now. This means each F atom already has 2 valence electrons, so it needs 6 more electrons to acquire a complete octet.
Thus, 6 valence electrons are placed as 3 lone pairs around each F atom in the structure, as shown below.
5.Complete the octet of the central atom
- Total valence electrons used tillstep 4= 3 single bonds + 3 (electrons placed around each F atom, shown as dots) =3(2) + 3(6) = 24 valence electrons.
- Total valence electrons available – electrons used till step 4 =28 – 24 = 4 valence electrons.
Thus, these 4 valence electrons are placed as 2 lone pairs around the central Cl atom in the ClF3.
In this way, the central atom chlorine in the ClF3 Lewis structure has a total of 10 valence electrons. It falls under the expanded octet rule. Chlorine (Cl) having d-subshells available can accommodate more than 8 valence electrons during chemical bonding.
As a final step, we just need to check the stability of the above Lewis structure and we can do so by using the formal charge concept.
6. Check the stability of the ClF3Lewis structure using the formal charge concept
The less the formal charge on the atoms of a molecule, the better the stability of its Lewis structure.
The formal charge can be calculated using the formula given below.
- Formal charge = [ valence electrons – nonbonding electrons- ½ (bonding electrons)]
Now let us count the formal charges present on ClF3atoms using this formula and the Lewis structure obtained instep 5.
For fluorine atom
- Valence electrons of fluorine = 7
- Bonding electrons = 1 single bond = 2 electrons
- Non-bonding electrons = 3 lone pairs = 6 electrons
- Formal charge = 7 – 6 – 2/2 = 7 – 6 – 1 = 7 – 7 = 0
For chlorine atom
- Valence electrons of chlorine = 7
- Bonding electrons = 3 single bonds = 3(2) = 6 electrons
- Non-bonding electrons = 2 lone pairs = 2(2) = 4 electrons
- Formal charge = 7 – 4 – 6/2 = 7 – 4 – 3 = 7 – 7 = 0
Zero formal charges present on all the bonded atoms in the ClF3molecule mark the stability of its Lewis structure.
Also check –
- Formal charge calculator
- Lewis structure calculator
- How to draw a lewis structure?
The ideal electron geometry of the chlorine trifluoride (ClF3) molecule is trigonal bipyramidal. But it is due to the 2 lone pairs of electrons present on the central chlorine atom that the molecule adopts a different molecular geometry or shape from its electron geometry i.e., T-shaped.
Molecular geometry of ClF3
ClF3is aT-shaped molecule. Two lone pairs situated on the central chlorine atom in the ClF3molecule set up a lone pair-lone pair and lone pair-bond pair repulsive effect which distorts the symmetry of the molecule.
Consequently, the molecule (ClF3) adopts an asymmetric T-shape. The 2 lone pairs occupy the equatorial positions while the 3 F-atoms occupy the two axial positions as well as one equatorial position in order to minimize the repulsive effect.
Electron geometry of ClF3
There are a total of 5 electron density regions around the central Cl atom in the ClF3molecule. According to the VSEPR concept, its ideal electron geometry istrigonal bipyramidal.
The electron geometry depends on the total number of electron density regions around the central atom i.e., total electron pairs in this case. It does not take into account whether an electron pair is a bond pair or a lone pair unlike that important for molecular geometry.
A quick and more straightforward way of finding the electron and molecular geometry or shape of a molecule such as ClF3is using the AXN method.
AXN is a simple formula to represent the number of atoms bonded to the central atom in a molecule and the number of lone pairs present on it.
It is used to predict the geometry or shape of a molecule using the VSEPR concept.
AXN notation for the ClF3molecule
- A in the AXN formula represents the central atom. In ClF3, chlorine (Cl) acts as the central atom so A= Cl.
- X denotes the atoms bonded to the central atom. 3 F atoms are bonded to the central Cl atom in the ClF3molecule thus X=3.
- N stands for the lone pairs present on the central atom. As 2 lone pairs of electrons are present on central chlorine in ClF3thus N=2.
So, the AXN generic formula for the ClF3molecule isAX3N2.
Now have a quick look at the VSEPR chart given below to identify where you find AX3N2.
The VSEPR chart confirms that molecules with an AX3N2 generic formula have a T-shape while their ideal electron geometry is trigonal bipyramidal, as we already noted down for the ClF3molecule.
Hybridization of ClF3
A short trick for finding the hybridization present in a molecule is to memorize the table given below. You can calculate the steric number of a molecule and use that against this table to determine its hybridization.
| Steric number | Hybridization |
| 2 | sp |
| 3 | sp2 |
| 4 | sp3 |
| 5 | sp3d |
| 6 | sp3d2 |
Now we need to find the steric number of ClF3. Use the below Formula to find the steric number of ClF3
- S.N. = N.A. + L.P.
- Where S.N. = Steric number
- N.A. = Number of atoms attached to the central atom
- L.P. = lone pairs on that central atom
Look at the ClF3 structure, three fluorine atoms are attached to the central atom(Chlorine) and two lone pairs are present on the central atom.
So, S.N. = 3 + 2 = 5
The steric number of central Cl in ClF3is 5 so it has sp3d hybridization.
The bond angle of ClF3
As the ClF3 central atom has 2 lone pair or 3 bond repulsion units and it formed T-shaped, Its F—Cl—F involving the axial F atoms bond angle is approx (175º) and F—Cl—F involving the one axial atom and one equatorial bond angle is approx (87.5º).
Also check:-How to determine bond angle?
Is ClF3 polar or non-polar? ClF3 is a polar molecule because it has an asymmetrical shape and the presence of 2 lone pair electrons leading to an unequal distribution of charge making this molecule polar in nature.
Also check-
- How to tell if a molecule is polar or nonpolar?
Let’s understand in depth why ClF3 is polar in nature with the help of three factors.
Three factors that indicate the polarity of ClF3
1. Electronegativity:
Electronegativity shows the tendency of an atom to pull electrons to itself. The higher the difference in electronegativity between atoms greater the polarity of that atom.
Clearly, in the ClF3 molecule, Fluorine is more electronegative than chlorine.
The electronegativity value of Chlorine is 3.16 and for fluorine, it is 4. The difference between the electronegativity of Fluorine and chlorine is more than 0.5.
Hence, the bond present in ClF3 is polar in nature.
2. Dipole moment
This is an accurate way to determine whether ClF3 is polar or non-polar. If the molecule has some net dipole moment then that molecule is polar in nature.
The higher the dipole moment of the molecule greater the polarity strength of that molecule.
The dipole moment is induced by the formation of negative and positive charges in the molecule.
Dipole moment diagram of ClF3
As you see in the above figure, dipole vector direction towards Fluorine. Because fluorine is more electronegative than Chlorine. Hence it attracts electrons towards itself and develops a partial negative charge.
The partial positive charge was also developed by Chlorine and we know separation of positive and negative charge leads to some dipole moment of the molecule.
So, these dipoles can’t be canceled out. Thus it makes ClF3 a polar molecule in nature.
3. Geometrical or molecular shape:
The geometry of ClF3 has a great influence on its polarity. As we know asymmetrical shape causes to become a molecule polar in nature.
From the lewis structure of ClF3, we know 2 lone pair present on its central atom thus it making the shape of ClF3 bent and causing unequal distribution of charges which induces a permanent dipole between atoms.
Also, the electron geometry of ClF3 is trigonal bipyramidal, and the molecular shape is T-Shaped which is a non-symmetrical shape.
Hence all these factors help to know whether ClF3 is polar or non-polar.