Structure, Molecular Geometry, and Hybridization of CH4 Lewis

Methane or CH4 is a naturally occurring and relatively abundant gas on Earth, making it a cost-effective fuel source. As it produces more light and heat when burned than coal, fossil fuels, or gasoline, it is preferred for energy generation.

This is one reason why the excessive production of methane has made it a significant greenhouse gas (GHG) that affects the Earth’s temperature and climate system.

Lewis structure is a graphical representation of the number of valence electrons in an atom.

In addition, the picture is useful for analysing how atomic bonds are forming to form a molecule and, eventually, a compound.

The Lewis diagram is created by representing valence electrons as dots drawn around the atom and by forecasting bond formation with lines.

These lines also indicate whether a single, double, or triple bond has formed, so facilitating the prediction of the core atom’s hybridization.

Valence Electrons

Valence electrons are those electrons in the outermost shell of an atom that participate in the creation of bonds.

These are the electrons that contribute to the creation of chemical bonds by being provided or received between atoms.

An atom can contain a maximum of eight valence electrons.

To determine the amount of valence electrons in a carbon atom, it is necessary to first determine its atomic number, six. Therefore, the carbon’s electrical arrangement will be 1s2 2s2 2p2.

As the p shell requires a total of six electrons, there are a deficiency of four electrons. This has resulted in the carbon atom having four valence electrons.

In contrast, the atomic number of the hydrogen atom is 1s1, indicating that its electronic configuration is 1s1.

Due to the deficiency of a single electron, the number of valence electrons in an atom of hydrogen is one.

Octet Rule

This rule states that a maximum of eight valence electrons can be drawn around an atom.

If we apply this approach, it is much simpler to recognise that carbon lacks four valence electrons while hydrogen requires only one.

CH4’s Lewis structure is designed to accommodate the valence electron requirements of each atom.

CH4 Lewis Structure

According to the lewis structure of carbon and hydrogen atoms, in order to construct a single CH4 molecule, eight more valence electrons are required to complete the shared bonding.

Here, we will learn, step by step, how to design the lewis dot structure for the CH4 molecule.

First, determine that a single CH4 molecule requires a total of sixteen valence electrons.

Next, a single CH4 molecule must search for electrons in order to establish a stable state.

For a single CH4 molecule, there are eight, as each carbon and hydrogen atom need four.

The following step is to determine the amount and kind of bond-forming atoms within a single CH4 molecule.

Every carbon and hydrogen atom forms a single shared covalent bond (C-H).

Finally, look for the centre atom, which is typically the only atom in a molecule. Carbon is the component of methane (CH4).

Now, illustrate the Lewis structure of methane (CH4) as seen below.

Methane’s Geometrical Structure (CH4)

Methane (CH4) is a tetrahedral molecule with no lone pairs on any atom. The Valence Shell Electron Pair Repulsion (VSEPR) theory provides an explanation for this behaviour.

This theory is used to anticipate the geometric structure of a molecule as well as its rationale.

As there is no distortion in the structure of the methane (CH4) molecule, according to this hypothesis, it is an ideal bent-shaped molecule or tetrahedron with a bond angle of 109.5° between the hydrogen-carbon-hydrogen atoms (H-C-H).

Due to the symmetrical nature of the CH4 molecule’s bonds, the charges on its atoms are evenly distributed and no polarisation occurs; thus, the Methane molecule is nonpolar.

Refer to the article about the polarity of CH4 for a fuller understanding.

Due to the presence of lone pairs and bond length between the core atom and the side atoms, there is a deviation from the ideal bond angle within a molecule.

It is evident from the Lewis structure that the carbon atom and four hydrogen atoms share an equal number of electrons.

It is the reason why methane’s structure is so stable in nature.

Combination of Methane (CH4)

Hybridization is the mathematical process of combining and overlapping at least two atomic orbitals within the same atom to create new hybrid orbitals with completely different orbitals and the same energy.

If we examine the hybridization state of the carbon atom in methane (CH4), we find that it is sp3.

Due to the fact that one 2s orbital and three 2p orbitals of carbon mix and overlap to generate four new hybrid orbitals of equal energy and similar shape, this occurs.

In addition, the new four sp3 hybrid orbitals exhibit 25% s orbital features and 75% p orbital characteristics.

Moreover, the four hydrogen atoms utilise these four new hybrid orbitals to form carbon-hydrogen (C-H) sigma bonds.

We know that the sole shared covalent bond has one sigma bond () but no pi bond ().

Thus, four sigma bonds are created in a methane molecule lacking a pi link, with each sigma bond contributing to the hybridization of the carbon atom.

Check read a companion article on the Intermolecular Forces of CH4 as well.

Molecular Orbital diagram of CH4

The molecular orbital diagram aids in establishing the hybridization type of a molecule by revealing how mixing and overlap have occurred.

Four sp3 hybrid orbitals of carbon mix and overlap with four 1s atomic orbitals of hydrogen, as depicted in the diagram.

Each carbon and hydrogen bond (C-H) is formed by the head-on overlap of the carbon’s lone occupied sp3 hybrid orbital with the hydrogen’s 1s orbital.

The fact that only sigma bonds conduct head-on overlapping whereas pi bonds undergo lateral overlapping confirms this.

As there are no pi bonds in the methane (CH4) molecule, there is only head-on overlap.

All four orbitals at the top of the diagram are empty, indicating a phase transition between carbon and hydrogen.

To place an electron in any of these orbitals, the bonding energy between the carbon and hydrogen atoms must be decreased.

On the other hand, all four orbitals at the bottom are occupied because their energy level is lower than that of the non-bonding energy level.

The orbital with the lowest energy is distributed uniformly throughout the molecule.

Conclusion

The Lewis structure of the methane (CH4) molecule consists of four solitary covalent bonds between carbon and hydrogen atoms.

Furthermore, since only sigma bonds exist and one 2s and three 2p carbon orbitals form four new hybrid orbitals, the hybridization of CH4 is sp3.

It is intriguing to note that regardless of the presence of sigma bonds, the new hybrid orbitals have p orbital properties.

In addition, the bond angle is the ideal tetrahedral angle of 109.5 degrees because there are no lone electron pairs on an atom.

Read more: Is ammonia (NH3) an acid or base?

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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