Phosphorus Valence Electrons (And How to Find them?)

So you have seen the above image by now, right?

Awesome! You can see that phosphorus has 5 valence electrons.

But how can you say that Phosphorus has 5 valence electrons
+
How can you find these valence electrons?

Let’s discuss this in short.

Phosphorus has 5 valence electrons because there are 5 electrons present in the outermost shell of the Phosphorus (P) atom.

Now let’s see how you can easily find the valence electrons of Phosphorus atom (P).

If you don’t want to read the texts, then you can also watch this video.

How to find the Valence Electrons? (2 Methods)

In order to find the valence electrons of Phosphorus atom (P), you can use two methods.

Method 1: From the Periodic Table

To find out the valence electrons of Phosphorus, you have to see the position of phosphorus in the periodic table.

More specifically, you have to see the group wise position of Phosphorus element in the periodic table.

From the above image, you can see that the Phosphorus (P) is present in the group 15 of periodic table.
(Note: Group 15 is also called group 5A).

So, as the phosphorus element is present in group 15, it has 5 valence electrons.

In this way, by knowing the position of phosphorus element in periodic table, you can easily find its valence electrons.

Now let’s see another method for finding the number of valence electrons in phosphorus.

Method 2: From the Electron Configuration

If you want to find the valence electrons of phosphorus from its electron configuration, then you should know its electron configuration first.

Now there are many methods to write the electron configurations, but here I will show you the easiest method, i.e by using Aufbau principle.

Aufbau principle: The Aufbau principle simply states that the orbitals with the lower energy are filled first and then the orbitals with higher energy levels are filled.

According to the Aufbau principle, the orbitals are filled in the following order:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, and so on.

Also the maximum number of electrons that can be accommodated in s, p, d & f orbitals are mentioned in the below table.

Orbitals	Maximum capacity of electrons [1]
s	2
p	6
d	10
f	14

Now let’s try to find the electron configuration of Phosphorus by using the Aufbau principle.

Electron Configuration of Phosphorus:

Follow the steps mentioned below to get the electron configuration of Phosphorus.

• To write the electron configuration of phosphorus, we should first know the total number of electrons present in a phosphorus atom.
• The phosphorus atom has a total of 15 electrons because its atomic number is 15 and it is a neutral atom. ^[2]
• Now we have to fill these 15 electrons in the atomic orbitals according to the Aufbau principle.
• According to the Aufbau principle, the electrons will be filled first in 1s orbital, then in 2s orbital, then in 2p orbital, and so on…
• So from the Aufbau principle, we can get the electron configuration of the phosphorus atom as 1s² 2s² 2p⁶ 3s² 3p³. ^[3]

Now in this electron configuration of phosphorus, we have to see the total number of electrons present in the highest energy level.

You can see in the electron configuration of phosphorus (1s² 2s² 2p⁶ 3s² 3p³) that the highest energy level is 3. And the total number of electrons present in this energy level is 2 + 3 = 5.

So by knowing the electron configuration, we have found that the Phosphorus has 5 valence electrons.

I hope you have understood the methods of finding the valence electrons in phosphorus. 

See more related topics for your practice;
Sulfur Valence Electrons
Chlorine Valence Electrons
Argon Valence Electrons
Gallium Valence Electrons
Germanium Valence Electrons