So you have seen the above image by now, right?
Let me explain the above image in short.
P2 lewis structure has two Phosphorus atoms (P) which contain a triple bond between them. There is 1 lone pair on both the Phosphorus atoms (P).
If you haven’t understood anything from the above image of P2 lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of P2.
So let’s move to the steps of drawing the lewis structure of P2.
Steps of drawing P2 lewis structure
Step 1: Find the total valence electrons in P2 molecule
In order to find the total valence electrons in a P2 molecule, first of all you should know the valence electrons present in a single phosphorus atom.
(Valence electrons are the electrons that are present in the outermost orbit of any atom.)
Here, I’ll tell you how you can easily find the valence electrons of phosphorus using a periodic table.
Total valence electrons in P2 molecule
→ Valence electrons given by phosphorus atom:
Phosphorus is group 15 element on the periodic table.  Hence the valence electrons present in phosphorus is 5.
You can see the 5 valence electrons present in the phosphorus atom as shown in the above image.
Total valence electrons in P2 molecule = 5(2) = 10.
Step 2: Select the central atom
For selecting the center atom, you have to remember that the atom which is less electronegative remains at the center.
Now here the given molecule is P2. Both the atoms are same, so you can select any of the atoms as a center atom.
Let’s assume the right side phosphorus as a central atom.
Step 3: Connect each atoms by putting an electron pair between them
Now in the P2 molecule, you have to put the electron pairs between both the phosphorus atoms (P).
This indicates that both the phosphorus (P) atoms are chemically bonded with each other in a P2 molecule.
Step 4: Make the outer atoms stable. Place the remaining valence electrons pair on the central atom.
Now in this step, you have to check the stability of the outer atom.
Here in the sketch of P2 molecule, we have assumed the right side phosphorus atom as a center atom. So the left side phosphorus is the outer atom.
Hence you have to make the left side phosphorus stable.
You can see in the below image that the left side phosphorus atom is forming an octet and hence it is stable.
Also, in step 1 we have calculated the total number of valence electrons present in the P2 molecule.
The P2 molecule has a total 10 valence electrons and out of these, only 8 valence electrons are used in the above sketch.
So the number of electrons which are left = 10 – 8 = 2.
You have to put these 2 electrons on the right side phosphorus atom in the above sketch of P2 molecule.
Now let’s proceed to the next step.
Step 5: Check the octet on the central atom. If it does not have octet, then shift the lone pair to form a double bond or triple bond.
In this step, you have to check whether the central (i.e right side) phosphorus atom (P) is stable or not.
In order to check the stability of this phosphorus (P) atom, we have to check whether it is forming an octet or not.
Unfortunately, this phosphorus atom is not forming an octet here. Phosphorus has only 4 electrons and it is unstable.
Now to make this phosphorus atom stable, you have to shift the electron pair from the left phosphorus atom.
But after shifting one electron pair, the right side phosphorus atom is still not forming an octet as it has only 6 electrons.
So again we have to shift one more electron pair from the left side phosphorus atom.
After shifting this electron pair, the right side phosphorus atom will get 2 more electrons and thus its total electrons will become 8.
You can see from the above picture that the right side phosphorus atom is forming an octet.
And hence this phosphorus atom is stable.
Now let’s proceed to the final step to check whether the lewis structure of P2 is stable or not.
Step 6: Check the stability of lewis structure
Now you have come to the final step in which you have to check the stability of lewis structure of P2.
The stability of lewis structure can be checked by using a concept of formal charge.
In short, now you have to find the formal charge on both the phosphorus (P) atoms present in the P2 molecule.
For calculating the formal charge, you have to use the following formula;
Formal charge = Valence electrons – (Bonding electrons)/2 – Nonbonding electrons
For Phosphorus (P) atom:
Valence electrons = 5 (because phosphorus is in group 15)
Bonding electrons = 6
Nonbonding electrons = 2
From the above calculations of formal charge, you can see that both the phosphorus (P) atoms have a “zero” formal charge.
This indicates that the above lewis structure of P2 is stable and there is no further change in the above structure of P2.
In the above lewis dot structure of P2, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of P2.
I hope you have completely understood all the above steps.
For more practice and better understanding, you can try other lewis structures listed below.
Try (or at least See) these lewis structures for better understanding:
|PI3 Lewis Structure
|NOBr Lewis Structure
|ClF2- Lewis Structure
|ClF4- Lewis Structure
|CIF3 Lewis Structure
|ClCN Lewis Structure
Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. He is a founder of Pediabay and is passionate about helping students through his easily digestible explanations.
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