CF4 is the molecular formula of Carbon Tetrafluoride and is the simplest fluorocarbon of all. It is a well-known haloalkane or halomethane having a high bond strength between the carbon and fluorine atoms becoming quite a stable compound. Moreover, the compound is also called tetrafluoromethane as it belongs to the group of fluoromethanes.
Carbon tetrafluorides are widely used to study fluorine chemistry to prepare organofluorine compounds. It is available in a colorless and inflammable gaseous state and usually transported in liquid form under very high pressure.
There exist many ways of preparing carbon tetrafluoride but the most commons industrial method is using hydrogen fluoride. When dichlorodifluoromethane reacts with hydrogen fluoride, it produces carbon tetrafluoride and hydrogen chloride.
CCl2F2 + 2HF ——> CF4 + 2HCl
Besides this, being a highly stable compound, the thermal decomposition of carbon tetrafluoride produces toxic gases of carbonyl fluoride and carbon monoxide.
This compound being slightly soluble in the water is used as an important refrigerant at a low temperature. Where this compound is used in electronic microfabrication, it is also one major greenhouse gas as it has a lifetime of more than 50,000 years making it a sound contributor to global warming.
Carbon Tetrafluoride (CF4) Lewis Structure
The Lewis structure is a diagrammatic representation of determining the position of valence electrons within an atom. Moreover, the diagram helps with determining how these valence electrons participate in the bond formation either by getting accepted or donated to another atom.
It is important to know in which shell the electrons are orbiting along with their energy levels to further study the hybridization of a molecule. It is the Lewis structure only by which we can study the molecular orbital diagram of a molecule.
As we know, to study the Lewis structure of any compound, we first need to analyze the structure of participating atoms. The atomic number of the carbon is 6 which makes its electronic configuration 1s2 2s2 2p2.
As we know, the p shell needs to accommodate 6 valence electrons in its outermost shell, there is a dearth of 4 valence electrons. This makes the valence electrons in carbon 4. Whereas, in the case of fluorine, its atomic number is 9 for which the electronic configuration is 1s2 2s2 2p5.
Besides this, we know chemistry is full of exceptions, so is the case with the fluorine atom. The valence electrons are also those which are present in the highest principal energy levels which are 2s and 2p for fluorine. This makes the valence electrons in the fluorine atom 7.
Here it is important to know first what the valence electrons are? The electrons available in the outermost shell of an atom are called valence electrons. Only these electrons participate in the bond formation as they are present farthest from the nucleus.
Due to this, the force of attraction by the nucleus does not reach effectively to these electrons. Even the slightest excitation by any nearby atom, these electrons readily bonds with them to form a new compound having new properties altogether.
Now, let’s learn to draw the Lewis structure of carbon tetrafluoride (CF4) with steps:
Step 1: Find the total number of valence electrons each carbon tetrafluoride (CF4) molecule has: It is 32 as 4 are coming from the carbon atom and 7 are coming from each fluorine atom.
Step 2: Find how many more valence electrons are needed by each carbon tetrafluoride (CF4) molecule: It is 8 as 4 more are needed by the carbon atom and one each by a fluorine atom.
Step 3: Look for the central atom in each carbon tetrafluoride (CF4) molecule: Usually, the central atom is the one that is present as the single entity within the molecule. They tend to make the maximum number of bonds with other participating atoms.
Step 4: Look for the type of bonds formed in each carbon tetrafluoride (CF4) molecule (single, double, or triple bond).
Only a single covalent shared bond is formed between the participating atoms.
Now merge all the above-mentioned points and draw the Lewis structure of the carbon tetrafluoride (CF4) molecule:
Carbon Tetrafluoride (CF4) Molecular Geometry
CF4 is a Penta-atomic molecule having a bond angle of 109.5° which gives rise to a tetrahedral shape.
It can be studied in detail with the help of the Valence Shell Electron Pair Repulsion (VSEPR) theory that in the presence of lone pair of electrons, the molecule tends to follow the ideal conditions.
Below is the attached VSEPR chart.
Carbon tetrafluoride (CF4) is the AX4E0 type structure where ‘A’ represents carbon, ‘X4’ represents four fluorine atoms and ‘E0’ represents zero lone pair of electrons.
Molecular geometry is the 3-dimensional diagram showing how electrons have bonded to determine a concrete value for bond angle, bond type, and molecular structure, and other geometrical parameters.
You can read about the molecular geometry of any molecule only after drawing its Lewis structure as it determines the number and positioning of the valence electrons within the molecule.
Carbon Tetrafluoride (CF4) Hybridization
The hybridization of the central atom in one carbon tetrafluoride molecule (CF4) is sp3. It is because one carbon atom and 4 fluorine atoms are bonding to complete all the involving octet.
Here, one 2s and three 2p orbitals of the same atom mix and overlap to produce four new atomic orbitals of equal energy.
Moreover, all the fluorine atoms use these newly produced four hybrid orbitals of the carbon atom to bond and form the carbon-hydrogen sigma bonds. This finally leads to the formation of the carbon fluoride molecule.
The single shared covalent bonds consist of only sigma bonds and no pi bonds at all. Due to this, the bond formation is quite strong and stable in the case of carbon tetrafluoride (CF4).
Another way to understand why hybridization is strong in carbon tetrafluoride is, sigma bonds are always formed by the linear and coaxial overlapping of the atomic orbitals which is stronger than the lateral overlapping of the pi bond. The molecules made up of only sigma bonds are highly reactive which is why they are quite responsive to polarity behavior.
Hybridization a pictorial representation of determining how the valence electrons of different atoms are bonding to give rise to a new molecule.
Here, the atomic orbitals of the same energy mix and overlaps to form new degenerated hybrid orbitals of the same energy.
It is a concept of quantum mechanics which says the atomic orbitals of similar energy can only participate in the hybridization process which is inclusive of both completely filled and partially filled orbitals having similar energy.
The mixing and overlapping of one s and one p orbital, two s and two p orbitals, one s and one d orbitals can take place only.
Carbon Tetrafluoride (CF4) Polarity
Polarity is behavior by which atoms tend to separate their electric charge forming two poles of positive and negative ends. Due to this separation of charges, a molecule becomes quite responsive to the nearby atom and tends to either repel or attract it.
In the case of carbon tetrafluoride (CF4), the molecule is found to be nonpolar.
The reason lies in the electronegativity values of each participating atom, which are carbon and fluorine in this case. Electronegativity is a mathematical way of determining how strongly an atom will attract the shared electrons towards itself. The higher the electronegativity value, the larger will be the force of attraction and vice versa.
The electronegativity value of carbon and fluorine are 2.5 and 4 where their difference is 1.5 which is more than 0.4. As per the law, if the electronegativity difference is less than 0.4, then the molecule is nonpolar otherwise polar. This means carbon tetrafluoride (CF4) is showing an anomaly where the electronegativity difference between the participating atoms is larger than 0.4 whereas it is a nonpolar molecule.
By generic rule, if we consider the electronegativity difference blindly, it would mean that each of the carbon-fluorine bonds is quite strong and polar. But chemistry is full of exception as stated earlier, it is the tetrahedral structure of the molecule which bring a symmetry within the structure.
You may also refer to CF4 Polarity reasons.
This symmetry originates from the fact that the carbon tetrafluoride has an ideal molecular geometry that cancels out the overall net dipole moment persisting on the molecule. Due to this, the carbon tetrafluoride (CF4) molecule is nonpolar in nature.
Carbon tetrafluoride (CF4) is a highly toxic chemical compound and is responsible for affecting the stratosphere by being one of the major greenhouse gases. By being a major refrigerant, this molecule is still in use by almost all major electronic industry players.
To know in detail the reactive behavior of carbon tetrafluoride (CF4), the starting point is its Lewis structure. It says the molecule has single shared covalent bonds made up of only sigma bonds which give rise to the high reactivity of carbon tetrafluoride (CF4).
Moreover, an anomaly has been noticed with carbon tetrafluoride (CF4), where the electronegativity difference between the participating atoms says the molecule is polar whereas the symmetry says it is nonpolar. Here symmetry wins, as it cancels out the overall net dipole moment neutralizing the molecule to zero.