Molecular Geometry, Hybridization, and Polarity of CH3F Lewis Structure

Fluoromethane, also known as CH3F or methyl fluoride, is a non-toxic compressed gas. Fluoromethane is a haloalkane, as the name implies (as a halide atom, fluoride, in this case, is bonded to the carbon atom in an alkane).

Fluoromethane is a greenhouse gas that belongs to the HFC (Hydro Fluoro Carbons) class. HFCs are linked to CFCs (Chlorofluorocarbons), however they don’t harm the ozone layer since they don’t produce reactive chlorine. The member of the HFC series with the smallest mass is methyl fluoride.

With a molecular weight of 37.015 g/mol, CH3F is a flammable, liquefiable gas. The molecule’s molecular geometry is tetrahedral, indicating sp3 hybridization.

The gas methyl fluoride is colourless. The gas has a nice odour that is similar to ether at high doses. The fluoromethane gas has a vapour pressure of 3.3 MPa.

Freon 41, HFC-41, and Halocarbon-41 are some of the other names for CH3F. The gas is used as an etching gas in plasma etch reactors during semiconductor manufacturing operations.

Methyl Fluoride’s Lewis Structure

Lewis structure is a standardised representation of valence shell electrons in a molecule. Electron-dot structures are another name for Lewis structures.

These structures are utilised to illustrate the bonding between the molecule’s atoms as well as the lone pairs.

The total number of electrons shown in the Lewis structure is determined by adding the number of valence electrons of each atom in the molecule, while non-valence electrons are not portrayed in the structure.

The steps to calculate the Lewis Structure of CH3F or Fluoromethane are as follows:

Step 1: Count how many valence electrons methyl fluoride has already:

Because the valence electrons of the atoms in the molecule are added together, CH3F (molecule) has 14 valence electrons.

Each hydrogen atom has one valence electron, while C has four (needs four more to complete its octet) and fluorine has seven (needs one more to complete its octet) (and requires one more to fill its valence shell).

Step 2: Write down how many extra valence electrons one methyl fluoride (CH3F) requires:

The sum of the valence electrons required by individual atoms is the overall amount of valence electrons required by the molecule.

As a result, the total number of valence electrons required will be 8, as stated in the previous stage (4 for carbon,1 for fluorine,1 for each hydrogen atom).

Step 3: Determine which atom in one methyl fluoride (CH3F) molecule would be best as the centre atom:

Because hydrogen can never be the core atom because it requires only one extra valence electron, carbon is the most suited atom. Fluorine is also more electronegative than carbon.

As a result, C will be the centre atom, with the three hydrogen atoms and the fluorine atom immediately connected to it to satisfy the valence electron requirement.

Step 4: Determine the type of bond formed between the methyl fluoride (CH3F) atoms (single, double, or triple):

Because all of the outside atoms require only one electron to fill their outer shell or valence shell, and there are no extra lone pairs, all of the bonds in the fluoromethane molecule will be single.

Step 5: The electron-dot structure or Lewis structure of methyl fluoride(CH3F) can be formed by considering all of the above-mentioned points as follows:

It can also be displayed in the format shown below.

A single bond is defined as the sharing of one pair of electrons between two atoms.

Methyl Fluoride Molecular Geometry (CH3F)

With carbon as the core atom, CH3F exhibits a tetrahedral shape with covalent bonds. There are no lone pairs in the molecule, however there are four sigma bonds (single bonds).

Fluoromethane has a similar structure to methane. Due to Fluorine’s increased electronegativity, the bond angles are different.

The bond length between C and F is roughly 0.14nm, and the bond energy is 552kJ/mol.

The hybridization of a molecule determines its molecular geometry or structure.

Fluoromethane Hybridization (CH3F)

The molecular geometry of fluoromethane or methyl fluoride is sp3 hybridization.

Despite the fact that the molecule is polar. The hybridization or molecular geometry is calculated as follows:

  1. Determine the total number of sigma bonds and lone pairs.

The number of sigma bonds in CH3F molecules is four (one C-F bond and three C-H bonds), while the number of lone pairs is zero.

  1. Subtract the steric number from the total number of lone pairs and sigma bonds to get the steric number.

The steric number in this case is 4, indicating sp3 hybridization, or tetrahedral molecular shape.

Polarity of Methyl Fluoride (CH3F)

Despite having sp3 hybridization, Methyl Fluoride or Fluoromethane is a polar chemical.

The polarity of the molecule is due to numerous factors, one of which being the difference in electronegativities of the Carbon and Fluorine atoms.

The polarity of the C-F bond is due to the fact that the fluorine atom is significantly more electronegative than the carbon atom.

Due to the unequal arrangement of valence electrons between the bonding atoms, the polarity of a bond impacts the bond length and strength.

The shared electron pair usually moves towards the more electronegative element.

To establish whether a molecule is polar or nonpolar, several criteria must be examined.

Electronegativity, dipole moment, and geometrical form are the main contributors. All three elements are intertwined.

Electronegativity is a measurement of an atom’s ability to attract a bound electron pair to itself.

The difference in the electronegativities of the atoms forming the bond determines the polarity of the bond.

The product of the charge on individual atoms and the distance between the centres of the two opposite charges is the dipole moment.

It is usually calculated in Debye units and is symbolised by the sign (D).

The C-F bond has a non-zero dipole moment, and the carbon atom has a partial positive charge and the fluorine atom has a partial negative charge.

As a result, the molecule’s overall dipole moment is non-zero.

Molecular Geometry: A molecule’s geometry or shape is determined by its hybridization, that is, the number of shared electrons and lone pairs.

The configuration of the dipoles inside the molecule determines the molecule’s dipole moment.

When dipoles are oriented opposite each other and have identical magnitudes, their effects tend to cancel out.

As a result, if all of a molecule’s dipoles are cancelled, the outcome is a nonpolar molecule. In general, symmetric molecules are polar because the dipoles opposite each other cancel out.

Because of the electronegativity mismatch between carbon and fluorine, CH3F molecules exhibit an asymmetric shape due to the difference in C-F bond length and C-H bond length.

The molecular geometry is influenced by the dipole moment and hybridization, whereas the dipole moment is influenced by the electronegativity.

After considering all of the aforementioned parameters, it’s clear that CH3F is a polar molecule with a dipole moment of 1.847D.

Applications

The drug can be used for a variety of purposes, including:

  1. Used in the fabrication of semiconductors and electronic components.

In many cases, CH3F is used as an etching gas.

  1. It’s been used in biological investigations.

In the presence of aerobic bacteria, CH3f or methyl fluoride can be used as a selective inhibitor of methane oxidation.

  1. HFC-41, also known as fluoromethane, is the smallest member of the CFC family and is used in refrigeration systems.

Furthermore, while methyl fluoride is an HFC (Hydro Fluoro Carbon) that is related to CFCs (Chlorofluorocarbons), it is safe for the ozone layer because no reactive chlorine is created.

Conclusion

CH3F or fluoromethane is a haloalkane created by substituting one hydrogen atom in methane with a fluorine atom. It is also known as Freon-41, HFC-41, methyl fluoride, Halocarbon-41, and trideuterio (fluoro)methane. With tetrahedral geometry, it is a combustible, non-toxic, liquefiable, colourless gas with a pleasant odour.

CH3F is a polar molecule with a molecular weight of 35.015g/mol, a C-F bond energy of 552kJ/mol, and a bond length of 0.139nm.

Fluoromethane has a melting point of 137.8 °C (216.0 °F) and a boiling point of 78.4 °C (109.1 °F).

While in the liquid condition, its density is roughly 1.4397 g/L 0.557 g/cm3 at 25 degrees Celsius. The vapour pressure of the gas is 3.3 MPa.

Read more: Molecular Geometry, Hybridization, and Polarity of COF2 Lewis Structure

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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