Carbon tetrafluoride (CF4) lewis dot structure, molecular geometry, polar or non-polar, bond angle
Carbon tetrafluoride is colorless and odorless gas with the chemical formula CF4. It is non-flammable gas and is used as a refrigerant in various industries. It is very stable due to the strength of its carbon-fluorine bond.
In this article, we will discuss Carbon tetrafluoride (CF4) lewis dot structure, its molecular geometry, is it polar or non-polar, bond angle, hybridization, etc.
CF4 is slightly soluble in water but miscible with various organic solvents. A high concentration of this gas can cause a deficiency of supply of air to the body which leads to abnormal breathing. This condition is known as asphyxiation.
Properties of Carbon tetrafluoride
It can become a narcotic at high temperatures.
It is nonflammable and soluble in chloroform and benzene.
It is a potent greenhouse gas.
It has a molar mass of 88.0043 g/mol.
It has a boiling point of −127.8 °C and a melting point of −183.6 °C.
How to draw lewis structure for CF4 (Carbon tetrafluoride)
CF4 lewis structure contains one carbon and four fluorine atom, carbon is in the center, and all fluorine atoms surround it. No lone pair is present on the central atom of the CF4 lewis dot structure but 3 lone pairs are present on each outer atom.
The lewis diagram of CF4 is very similar to CCl4. Let’s see step by step how to draw its Lewis structure with all explanations.
Follow some steps for drawing the lewis dot structure of CF4
1. Count total valence electron in CF4
The electrons found in the outermost shell of an atom are called valence electrons. To find the valence electrons in the CF4 molecule, look at the periodic group of each atom present in it. As carbon is situated in the 14th group and fluorine in the 17th. Therefore, the valence electron present in carbon is 4 and for fluorine, it is 7.
Now to find valence electrons in the CF4 molecule, simply add the carbon and fluorine valence electrons.
∴ Total valence electron available for drawing the CF4 lewis structure = 4 + 7*4 = 32 electrons [∴CF4 has four fluorine atom]
2. Find the least electronegative atom and placed it at center
Here we need to find the least electronegative atom in the CF4 molecule so that we can place it at the center in the lewis diagram. Electronegativity always increases from left to right in the periodic table. But we know fluorine is the most electronegative element in chemistry. So, fluorine always goes outside in lewis’s diagram.
Hence put carbon at the center in the lewis diagram and fluorine spaced evenly around it.
3. Connect outer atom to central atom with a single bond
Now we have to connect each outer atom to the central atom with a single bond to initiate the lewis structure of CF4. So, connect all fluorine atoms to the carbon atoms with the help of a single bond.
As you see in the above structure, we connected all fluorine atoms to the carbon atoms with the help of 4 single bonds. And every single bond has 2 electrons in it.
Therefore, 4 single bonds mean 8 electrons we used in the above structure from the total of 32 valence electrons available for drawing the CF4 lewis dot structure.
∴ (32 – 8) = 24 valence electrons.
Now, the remaining valence electrons we have are 24.
4. Place remaining valence electrons starting from outer atom first
In this step, we need to put the remaining valence electrons around the outer atom first to complete their octet. So, in a CF4 molecule, the outer atom is fluorine and fluorine needs 8 electrons in its valence shell to complete its octet.
So, start putting the remaining valence electrons around fluorine atoms first to complete their octet.
Lewis dot structure of CF4
As you see in the above CF4 lewis dot structure, we put 6 electrons around each fluorine atom because fluorine already shares the 2 electrons with the help of a single bond present in between carbon and fluorine. So, each fluorine has 8 electrons around them and that is enough for completing their octet.
Now, carbon which is the central atom also needs 8 electrons in its valence shell to complete the octet rule. But by looking at the above structure, we come to know carbon already sharing 8 electrons with the help of 4 single bonds connect to fluorine atoms.
So, both atoms (Carbon and fluorine) of the CF4 molecule complete their octet comfortably.
Hence, we got our stable Carbon tetrafluoride lewis structure.
What are the electron and molecular geometry of CF4?
The molecular geometry of CF4 is Tetrahedral. Since all four fluorine (F) atoms are attached to a carbon (C) atom, and no lone pair is present on the central atom. According to the VSEPR theory, any molecule that has four bonded atoms linked with a central atom and no lone pair present on the central atom acquires the tetrahedral geometry.
Also, all fluorine atoms bonded to carbon atoms lie at the corners of the tetrahedron with a 109.5ºbond angle between them.
The electron geometry of CF4 is also tetrahedral.
Let’s see how to find the electron and molecular geometry of the CF4 molecule:-
Follow some steps to find CF4 molecular geometry
1. Find the Number of lone pairs present on the central atom of the CF4 lewis dot structure
The lone pair is non-bonding electrons that don’t take part in chemical bonding. As per the CF4 lewis structure, no lone pair is present on the central atom (carbon).
Or you can check the lone pair on the central atom by the formula given below-
So, carbon is the central atom that is attached to four fluorine atoms with the help of a single bond and it has 4 valence electrons in its outermost shell.
So, L.P. on carbon = (4 – 4)/2
= 0
∴ The lone pair on the central atom of the CF4 molecule is 0.
2. Find hybridization number of CF4
“Hybridization is the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., then the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory”.
To find the hybridization of an atom we have to look at its hybridization number or steric number.
Use the given formula to find the hybridization number for CF4.
∴ Hybridization number of CF4 = (Number of atoms attached to Carbon + Lone pair on Carbon)
As per the CF4 lewis structure, carbon has four atoms(fluorine) attached to it and no lone pair present on it.
So, Hybridization number = 4 + 0
= 4
So, the hybridization number for CF4 is 4 which means it has Sp³ hybridization.
Hybridization number
Hybridization
1
S
2
Sp
3
Sp²
4
Sp³
5
Sp³d
6
Sp³d²
3. Use VSEPR theory or AXN method to determine CF4 molecular geometry
“The shape of a molecule depends upon the number of valence shell electron pairs around the central atom.”
According to Valence shell electron pair repulsion theory if the molecule central atom has zero lone pair and sp³ hybridization then the molecular geometry of that molecule will be tetrahedral.
Molecular geometry of CF4
Now use another method to find the molecular geometry of CF4. AXN method–
As per CF4 lewis structure, AXN notation of it follow as-
A = Carbon is a central atom.
X = Four fluorine atoms attached to the carbon.
N = No lone pair present on the carbon atom.
So, the generic formula for CF4 is AX4.
According to the VSEPR chart, if the molecule has AX4 generic formula then the molecular shape and electron geometry of that molecule will be tetrahedral.
Bonded atoms
Lone pair
Generic formula
Hybridization
Molecular geometry
Electron geometry
1
0
AX
S
Linear
Linear
2
0
AX2
Sp
Linear
Linear
1
1
AXN
Sp
Linear
Linear
3
0
AX3
Sp²
Trigonal planar
Trigonal planar
2
1
AX2N
Sp²
Bent
Trigonal planar
1
2
AXN2
Sp²
Linear
Trigonal planar
4
0
AX4
Sp³
Tetrahedral
Tetrahedral
3
1
AX3N1
Sp³
Trigonal pyramid
Tetrahedral
2
2
AX2N2
Sp³
Bent
Tetrahedral
1
3
AXN3
Sp³
Linear
Tetrahedral
3
2
AX3N2
Sp³d
T-shaped
Trigonal bipyramidal
5
1
AX5N
Sp³d²
Square pyramidal
Octahedral
Carbon tetrafluoride polarity: is CF4 polar or nonpolar
Is CF4 polar or non-polar? The CF4 molecule is nonpolar due to its symmetrical tetrahedral structure but the bond present in it polar.
The tetrahedral geometry results in a symmetrical arrangement of polar bonds around the carbon atom, as a result, the same charges are distributed within the molecule which helps to cancel out the bond dipole. The net dipole moment of CF4 is zero.
Let’s take an overview of the important factors for determining the polarity of CF4.
Three factors that indicate the polarity of CF4
1. Electronegativity:
Higher the electronegativity of an atom more is the power of attracting electrons towards itself. The electronegativity for fluorine is 3.98 and for carbon, it is 2.5. These electronegativity difference between the carbon and fluorine atom makes each bond polar(C-F).
Each individual C-F polar bond can easily be canceled out due to the symmetrical tetrahedral shape of the CF4 molecule.
2. Dipole moment
The net dipole moment of CF4 is zero. As the fluorine is more electronegative than carbon. So, it attracts more electrons towards itself, which generates an electric dipole represented as a vector, direction from carbon to the fluorine atom.
More electronegative atoms generate a partial negative charge on it whereas other ones generate a positive charge on it. This separation of positive and negative charges is measured by dipole moment.
The vector sum of these four individuals bond(C-F) dipole is zero because all fluorine atoms are pulling electrons from carbon is in an equal and opposite direction.
So, all C-F polar bonds canceled out leaving this molecule as nonpolar in nature.
3. Geometrical or molecular shape
The molecular geometry of CF4 is tetrahedral with all same atoms in the surrounding. “If all four surrounding atoms are the same in a tetrahedral, then the molecule will always be nonpolar. The only exception is if for some reason one or more of the surrounding atoms had a lone pair.”
As the tetrahedral shape of the CF4 molecule results in the direction of the dipole moment of anyone bond being opposite to the vector sum of the other three dipoles. Hence, they will cancel out each other and generate zero dipole moment in the molecule.
What is the formal charge in CF4 lewis structure and how to calculate it?
The formal charge of CF4 shows that which atom(carbon or fluorine) has a more positive or negative charge present on it.
To calculate the formal charge in CF4 lewis dot structure. Use this equation given below:
Now we will calculate the formal charge on carbon which is the central atom in the CF4 lewis structure.
⇒ Valence electron of carbon = 4
⇒ Non-bonding (lone pair) electrons on carbon = 0
⇒ Bonding electrons attached to carbon = 8 [∴ 4 single bonds that contain 8 electrons]
∴ (4 – 0 – 8/2)
= 0 is the formal charge on carbon in the CF4 molecule.
FAQ
How many bonded pairs and lone pairs of electrons are present in the CF4 lewis structure?
According to the CF4 lewis dot structure, the bonded pair of electrons in CF4 is 8(4 single bonds) and the lone pair of electrons is 24(3 lone pairs on each fluorine atom).
Are the lewis structure and molecular geometry of CF4 is same as CCl4?
Yes, the molecular geometry and lewis structure of CF4 is the same as CCl4 because of the same generic formula(AX4) for both of them.
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/
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