Methanol (CH3OH | Methyl Alcohol) Lewis Structure and Steps of Drawing
Methanol (CH3OH) is the simplest alcohol which has only one carbon atom. According to the lewis structure of methanol, it has one O-H bond, three C-H bonds and one C-O bond. There are 2 lone pairs on oxygen atom. There are total of 14 electrons in valence shells in the overall molecule as lone pairs and bonds.
CH3OH lewis structure
There are only five bonds in CH3OH lewis structure. All of them are sigma bonds.
Steps of drawing lewis structure of CH3OH
There are several steps to draw the lewis structure of CH3OH and we are going to use those steps in detail in this tutorial.
- Find total number of electrons of the valance shells of hydrogen, oxygen atoms and carbon atom
- Determine total electrons pairs as lone pairs and bonds
- Find center atom and construct the basic sketch
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Total number of electrons of the valance shells of CH3OH
There are 3 elements in methanol molecule; hydrogen, carbon and oxygen. Hydrogen is a group IA element and has only one electron in its valence shell. Oxygen belongs to the group VIA and has six electrons in its last shell (valence shell). Carbon atom has 4 electrons in its last shell because it is a IVA group element. Now we know how many electrons are includes in valence shells of atoms.
To find out total valence electrons given by a particular element in a molecule or ion, you should multiply number of electrons of the valance shell by the number of atoms of that element in respective molecule.
- valence electrons given by hydrogen atoms = 1 * 4 = 4
- valence electrons given by carbon atom = 4 * 1 = 4
- valence electrons given by oxygen atom = 6 * 1 = 6
- Total valence electrons = 4 + 4 + 6 = 14
Total valence electrons pairs
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, CH3OH, total pairs of electrons are 7 (14/2) in their valence shells.
Center atom and basic sketch of CH3OH
To be the center atom, ability of having greater valance and being most electropositive element in the molecule are leading facts.
However, CH3OH is a simple molecule. We know that carbon atom has the highest chance to be center atoms than hydrogen and oxygen atoms because carbon has the highest valence (4) from those 3 elements in methanol.
Basic sketch of CH3OH is given below.
Lone pairs on atoms
After deciding the center atom and sketch of CH3OH molecule, lone pairs are marked on atoms. Remember that, there are total of 7 electron pairs to mark on atoms as bonds and lone pairs.
- There are already 5 bonds in the above drawn sketch. Now only 2 (7-5) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms. But, hydrogen atoms cannot keep more than two electron in its last shell and there is no possibility mark lone pairs furthermore on hydrogen atoms.
- Therefore, then mark remaining electrons pairs on oxygen atom; oxygen atom will take 2 lone pairs to get fulfilled its octal. Now all 2 lone pairs were marked and no more lone pairs to mark on carbon atom.
Mark charges on atoms check the stability and minimize charges on atoms by converting lone pairs to bonds
There are no charges on one atoms. Therefore, we don't need to doing the step of reducing charges to get the most stable structure.
Questions
How CH3OH lewis structure is different from CH3Br lewis structure?
There is an extra hydrognen atom in CH3OH. Because CH3OH is slightly acidic, there should be a O-H bond to remove H+ ion.
How many lone pairs are there in methanol lewis structure
Only oxygen atoms has 2 lone pairs in methanol.