Methane (CH4) lewis dot structure, molecular geometry or shape, electron geometry, bond angle, valence electrons
Methane is a colorless and odorless gas formed from one atom of carbon and four atoms of hydrogen having the chemical formula CH4. It is the simplest of saturated hydrocarbons. It is used for the generation of electricity by burning as a fuel in a steam generator or gas turbine.
In this article, we will discuss Methane (CH4) lewis dot structure, molecular geometry, electron geometry, hybridization, polar or nonpolar, its bond angle, valence electrons, etc.
Methane is mainly used as fuel for turbines, water heaters, ovens, etc. It is also used in industrial chemical processes to prepare other chemicals.
CH4 Lewis structure is made up of one carbon (C) atom and four hydrogens (H) atoms. The carbon atom is in the middle position and hydrogen is in the surrounding position. There are no lone pair electrons present in the lewis dot structure of CH4.
Let’s see how to draw the lewis structure of CH4 by following some simple steps-
Simple steps for drawing the Lewis dot structure for CH4
1. Count total valence electrons in CH4
In the first step, we have to find how many valence electrons are there in CH4, so that we can distribute them around central and terminal atoms with the goal of completing their octet shell.
You have two ways to find out the valence electron for a particular atom, either by looking at their periodic group or by writing their electronic configuration. We will use the method of the periodic group for finding the valence electron in CH4.
The carbon atom belongs to Group 4A or 14A in the periodic table, hence, it has a 4 valence electron in its outermost shell whereas the hydrogen atom belongs to Group 1A, hence, it has only 1 valence electron in its outermost shell.
∴ Total valence electron available for drawing the CH4 lewis structure = 4 + 1×4 = 8 valence electrons [∴CH4 has four hydrogen atoms and one carbon atom]
2. Find the least electronegative atom and placed it at center
Whenever hydrogen is present in any molecule then it doesn’t matter which atom is less or more electronegative, hydrogen always goes outside in a lewis diagram and it needs only two electrons to complete its outer shell.
So, place all Hydrogen atoms outside in the lewis diagram and the Carbon atom at the central position.
3. Connect each outer atom to the central atom with a single bond
In this step, we will simply connect each outer atom (which is hydrogen in the CH4 molecule) to the central atom(carbon) with the help of a single bond.
Now look at this structure and count how many electrons we used till now and how many are left.
As four single bonds are used in the above structure that contains 8 electrons(1 single bond means 2 electrons) and we have a total of 8 valence electrons are available for drawing the CH4 lewis structure.
∴ (8 – 8) = 0 valence electrons
So, we used all available valence electrons in the above structure, now just counting the electrons in the valence or outer shell of each atom to know if they completed their octet or not.
“The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell”.
The atom which have less or more than 8 electrons in valence shell, they are classified as Exceptional to the octet rule.
The carbon atom needs 8 electrons in its valence shell to complete the octet, if you see the above structure, the carbon central atom is attached with four single bonds, which means, it has already 8 electrons in its outer shell, hence, the carbon atom completed its octet comfortably.
Note: The hydrogen atom only requires two valence electrons for completing the octet as it is exceptional to the octet.
So, in the above structure, each hydrogen atom is attached to the single bond, which means, they already have two electrons in their outer shell, hence, hydrogen atoms also completed their octet rule comfortably.
As you see in this CH4 lewis structure, the carbon central atom and hydrogen atom completed their octet, and everything looks fine, but, for the sake of satisfaction, we should also determine the formal charge in the above structure to know whether it is stable or not.
4. Check the stability with the help of a formal charge concept
A formal charge is the charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms.
The structure with a formal charge close to zero or zero is the best and most stable lewis structure.
To calculate the formal charge in the CH4 lewis structure. Use the formula given below-
Let’s start with the central atom which is carbon in the CH4 molecule.
For carbon atoms:
⇒ Valence electrons of carbon = 4
⇒ Lone pair electrons on carbon = 0
⇒ Bonding electrons of carbon(4 single bonds) = 8
∴ (4 – 0 – 8/2) = 0 formal charge on the carbon central atom.
Each hydrogen atom in the CH4 lewis structure has the same number of bonded pair electrons, hence, just count the formal charge for just one hydrogen atom, rest will follow it.
For hydrogen atom
⇒ Valence electrons of hydrogen = 1
⇒ Lone pair electrons on hydrogen = 0
⇒ Bonding electrons around hydrogen (1 single bond) = 2
∴ (1 – 0 – 2/2) = o formal charge on each hydrogen atom.
Hence, each atom in CH4 gets a formal charge equal to zero.
Therefore, the above lewis structure of CH4 (Methane) is the most stable, appropriate, and reliable.
What are the electron and molecular geometry of CH4 (Methane)?
The molecular geometry of CH4 is Tetrahedral.
The carbon (C) central atom is located in the center of the tetrahedron, while the four hydrogens (H) atoms are located on the vertices.
These atoms repel each other in a way that the final molecular shape of CH4 appears like a Tetrahedral.
In CH4, the carbon central atom has no lone pair and is attached to the four hydrogen atoms with the help of a single covalent bond. So, there are four regions of electron density around the carbon central atom.
The electron pair around the carbon central atom will repel each other and tried to go far from each other, they will take the position where repulsion becomes minimum between them.
According to the VSEPR theory, “in most of the cases, the central atom with four regions of density adopt a tetrahedral structure because repulsion is minimum in electron pairs at this position.”
“Four electron pairs are distributed in a tetrahedral shape.
If these are all bond pairs the molecular geometry is tetrahedral (e.g. CH4)”.
In the above figure, the red lines outline the tetrahedron and the black line shows the bonded pair or electron pair formed between carbon and hydrogen. “The carbon atom is located in the center of the tetrahedron, while the four hydrogens atoms are located on the vertices.”
So, there are four bonding pairs formed in CH4 molecule, hence, according to the VSEPR theory, they will repel each other, as a result, all corners atoms(hydrogens) spread out as much as they can and takes the place where the repulsion is minimum and stability is much better.
Hence, the final molecular geometry of CH4 appears like a regular tetrahedron with a bond angle ∠H−C−H =109.5°.
If you can’t visualize the molecular geometry of CH4, then theoretically we can use an AXN method and VSEPR chart to determine its shape.
AXN is a simple formula that represents the number of the bonded atom and lone pair on the central atom to predict the shape of the molecule using the VSEPR chart.
AXN notation for CH4 molecule:
A denotes the central atom, so, in the CH4 molecule, carbon is the central atom. A = Carbon
X denotes the bonded atoms to the central atom, as we know, the carbon central atom is bonded with four hydrogen atoms. Therefore, X = 4
N denotes the lone pair on the central atom, as per CH4 lewis structure, the carbon central atom doesn’t contain any lone pair. Hence, N = 0
So, the AXN notation for the CH4 molecule becomes AX4N0 or AX4.
As per the VSEPR chart, if a molecule’s central atom is attached with four bonded atoms and has contained zero lone pair then the molecular geometry of that molecule is tetrahedral, and its electron geometry is also tetrahedral.
Hence, the molecular geometry for CH4 is tetrahedral and its electron geometry is also tetrahedral.
CH4 molecular geometry/shape
Hybridization of CH4
Let’s find the hybridization of CH4 through the steric number of its central atom.
“Steric number is the addition of a total number of bonded atoms around a central atom and the lone pair present on it.”
∴ Steric number of CH4 = (Number of bonded atoms attached to carbon atom + Lone pair on carbon atom)
As per the lewis structure of CH4, the central Carbon atom is bonded with four hydrogen atoms and it doesn’t have any lone pair.
∴ Steric number of CH4 = (4 + 0) = 4
Steric number
Hybridization
1
S
2
Sp
3
Sp²
4
Sp³
5
Sp³d
6
Sp³d²
So, for a steric number of four, we get the Sp3 hybridization on a carbon atom in the CH4 molecule.
The newly produced hybrid orbitals in CH4 molecule have 25% behavior of the s orbital and 75% behavior of the p orbital.
The bond angle of CH4
As we know the molecular geometry of CH4 is regular tetrahedral with no distortion, hence, according to the VSEPR theory, for a regular tetrahedral structure, the bonded atoms around the central atom will spread at an angle of approx 109.5° to minimize the repulsion and attains stability.
Well, we know the polar molecule has some dipole moment because of unequal distribution of charges whereas the non-polar molecule has an equal distribution of charges that cause zero dipole moment because they cancel out each other due to the symmetrical shape of the molecule.
Is Methane (CH4) polar or non-polar? CH4 is a non-polar molecule because it contains four bonds(C-H) that are arranged symmetrically in tetrahedral geometrical shapes. Due to this, dipole moment generated on each side along C-H will cancel out each other making an overall nonpolar molecule.
Let’s understand whether CH4 is polar or non-polar in detail.
Why is the molecular geometry of CH4 is same as its electron geometry?
The molecular geometry of CH4 is tetrahedral and its electron geometry is also tetrahedral.
Because as per VSEPR theory, molecular shape considers only bond pairs
While electron geometry considers bonded atoms as well as lone pairs present on the central atom.
According to the lewis structure of CH4, the central atom(carbon) doesn’t contain any lone pair on it.
Hence, only bonded atoms are used to determine the geometry of CH4.
Therefore, the Molecular geometry of CH4 = Electron geometry of CH4 [∴ no lone pair on central atom of CH4]
How many lone pairs and bond pairs are present around the carbon central atom in the CH4 lewis structure?
According to the lewis dot structure of CH4, the Carbon central atom doesn’t contain any lone pair but is attached to the four hydrogen atoms with the help of four bonded pairs.
How many valence electrons are present in the CH4 lewis structure?
⇒ Total valence electron in Carbon = 4
⇒ Total valence electron in Hydrogen = 1
∴ Total valence electron available for drawing the CH4 lewis structure = 4 + 1*4 = 8 valence electrons [∴CH4 has four hydrogen atoms and one carbon atom]
The total valence electron available for drawing the Methane (CH4) lewis structure is 8.
The steric number of the central atoms in methane is 4 which ensures that it has an Sp3 hybridization.
CH4 is a nonpolar molecule due to its symmetrical geometry that causes uniform charge distribution all over the atom leading to a zero net dipole moment and making this molecule non-polar in nature.
The Methane (CH4) lewis structure is made up of one carbon atom that is situated at the middle position and four hydrogens atoms that are at the surrounding position.
CH4 molecular geometry is tetrahedral and its electron geometry is also tetrahedral.
The bond angle of CH4 is 109.5º.
Lewis dot structure of CH4 contains only 4 bonded pairs(8 shared electrons) and doesn’t contain any lone pair electrons in the molecule.
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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