P4 Lewis structure

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P4 Lewis Structure
P4 Lewis structure

P4 (phosphorus) has four phosphorus atoms.

In the P4 Lewis structure, there are six single bonds between the four phosphorus atoms, and on each phosphorus atom, there is one lone pair.


Here’s how you can easily draw the P4 Lewis structure step by step:

#1 Draw a rough skeleton structure
#2 Mention lone pairs on the atoms
#3 If needed, mention formal charges on the atoms

Now, let’s take a closer look at each step mentioned above.

#1 Draw a rough skeleton structure

  • First, determine the total number of valence electrons
Periodic table

In the periodic table, phosphorus lies in group 15. Hence, phosphorus has five valence electrons.

Since P4 has four phosphorus atoms, so…

Valence electrons of four phosphorus atoms = 5 × 4 = 20

So the total valence electrons = 20

  • Second, find the total electron pairs

We have a total of 20 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 20 ÷ 2 = 10

  • Third, determine the central atom

Here, there are four atoms and all atoms are phosphorus, so we can assume any one as the central atom.

Let’s assume that the central atom is center phosphorus.

  • And finally, draw the rough sketch
P4 Lewis Structure (Step 1)
Rough sketch of P4 Lewis structure

#2 Mention lone pairs on the atoms

Here, we have a total of 10 electron pairs. And six P — P bonds are already marked. So we have to only mark the remaining four electron pairs as lone pairs on the sketch.

Also remember that phosphorus is a period 3 element, so it can keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are one top phosphorus and two bottom phosphorus.

So for each phosphorus, there is one lone pair.

Mark the lone pairs on the sketch as follows:

P4 Lewis Structure (Step 2)
Lone pairs marked, and got the stable Lewis structure of P4

#3 If needed, mention formal charges on the atoms

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For each phosphorus atom, formal charge = 5 – 2 – ½ (6) = 0

Here, the atoms do not have charges, so no need to mark the charges.

In the above structure, you can see that the central atom (center phosphorus) forms an octet. And the outside atoms (other phosphorus) also form an octet. Hence, the octet rule is satisfied.

Therefore, this structure is the stable Lewis structure of P4.

Next: C2H2Cl2 Lewis structure


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