P_{4} (phosphorus) has **four phosphorus** atoms. In the lewis structure of P_{4}, there are six single bonds between the four phosphorus atoms, and on each phosphorus atom, there is one lone pair.

## Steps

Here’s how you can draw the P_{4} lewis structure step by step.

Step #1: draw sketch

Step #2: mark lone pairs

Step #3: mark charges (if there are)

Let’s break down each step in detail.

### #1 Draw Sketch

- First, determine the total number of valence electrons

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

Since P_{4} 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

### #2 Mark Lone Pairs

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:

### #3 Mark Charges

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.

And in the above structure, you can see that the central atom (center phosphorus) forms an octet. Hence, the octet rule is satisfied.

Therefore, this structure is the stable lewis structure of P_{4}.

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