# Chlorine(Cl) electron configuration and orbital diagram

Chlorine(Cl) is the 17th element in the periodic table and its symbol is ‘Cl’. The electron configuration of chlorine and the orbital diagram is the main topic in this article. Also, valency and **valence electrons of chlorine**, and compound formation, bond formation have been discussed. Hopefully, after reading this article you will know in detail about this.

The total number of electrons in chlorine is seventeen. These electrons are arranged according to specific rules of different orbits. The arrangement of electrons in different orbits and orbitals of an atom in a certain order is called electron configuration. The electron configuration of chlorine(Cl) atoms can be done in two ways.

- Electron configuration through orbit
- Electron configuration through orbital

Electron configuration through orbitals follows different principles. For example Aufbau principle, Hund’s principle, Pauli’s exclusion principle. There is an article published on this site detailing the **electron configuration**, you can read it if you want.

Table of Contents

## Chlorine(Cl) electron configuration through orbit

Scientist Niels Bohr was the first to give an idea of the atom’s orbit. He provided a model of the atom in 1913. The complete idea of the orbit is given there. The electrons of the atom revolve around the nucleus in a certain circular path. These circular paths are called orbit(shell). These orbits are expressed by n. [n = 1,2,3,4 . . . The serial number of the orbit]

K is the name of the first orbit, L is the second, M is the third, N is the name of the fourth orbit. The electron holding capacity of each orbit is 2n^{2}.

For example,

- n = 1 for K orbit.

The electron holding capacity of K orbit is 2n^{2}= 2 × 1^{2}= 2 electrons. - For L orbit, n = 2.

The electron holding capacity of the L orbit is 2n^{2}= 2 × 2^{2}= 8 electrons. - n=3 for M orbit.

The maximum electron holding capacity in M orbit is 2n^{2}= 2 × 3^{2 }= 18 electrons. - n=4 for N orbit.

The maximum electron holding capacity in N orbit is 2n^{2}= 2 × 4^{2}= 32 electrons.

Therefore, the maximum electron holding capacity in the first shell is two, the second shell is eight and the 3rd shell can have a maximum of eighteen electrons. The atomic number is the number of electrons in that element. The atomic number of chlorine is 17. That is, the number of electrons in chlorine is seventeen.

Therefore, the chlorine atom will have two electrons in the first shell, eight in the 2nd orbit and seven electrons in the 3rd shell. Therefore, the order of the number of electrons in each shell of chlorine(Cl) atom is 2, 8, 7.

Electrons can be arranged correctly through orbits from elements 1 to 18. The electron configuration of an element with an atomic number greater than 18 cannot be properly determined according to the Bohr atomic model. The **electron configuration of all the elements** can be done through orbital diagrams.

## Electron configuration of chlorine(Cl) through orbital

The German physicist Aufbau first proposed an idea of electron configuration through sub-orbits. The Aufbau method is to do electron configuration through the sub-energy level. These sub-orbitals are expressed by ‘l’.

The Aufbau principle is that the electrons present in the atom will first complete the lowest energy orbital and then gradually continue to complete the higher energy orbital. These orbitals are named s, p, d, f. The electron holding capacity of these orbitals is s = 2, p = 6, d = 10 and f = 14. The Aufbau electron configuration method is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d.

The first two electrons of chlorine(Cl) enter the 1s orbital. The s-orbital can have a maximum of two electrons. Therefore, the next two electrons enter the 2s orbital. The p-orbital can have a maximum of six electrons. So, the next six electrons enter the 2p orbital. The second orbit is now full. So, the remaining electrons will enter the third orbit. Then two electrons will enter the 3s orbital of the third orbit and the remaining five electrons will be in the 3p orbital. **Therefore, the chlorine(Cl) electron configuration will be 1s ^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5}.**

## How to write the orbital diagram for chlorine(Cl)?

To create an orbital diagram of an atom, you first need to know Hund’s principle and Pauli’s exclusion principle. Hund’s principle is that electrons in different orbitals with the same energy would be positioned in such a way that they could be in the unpaired state of maximum number and the spin of the unpaired electrons will be one-way. And Pauli’s exclusion principle is that the value of four quantum numbers of two electrons in an atom cannot be the same. To write the orbital diagram of chlorine(Cl), you have to do the electron configuration of chlorine. Which has been discussed in detail above.

1s is the closest and lowest energy orbital to the nucleus. Therefore, the electron will first enter the 1s orbital. According to Hund’s principle, the first electron will enter in the clockwise direction and the next electron will enter the 1s orbital in the anti-clockwise direction. The 1s orbital is now filled with two electrons. The next two electrons will enter the 2s orbital just like the 1s orbital.

The next three electrons will enter the 2p orbital in the clockwise direction and the next three electrons will enter the 2p orbital in the anti-clockwise direction. The next two electrons will enter the 3s orbital and the next three electrons will enter the 3p orbital in the clockwise direction and the remaining two electrons will enter the 3p orbital in the anti-clockwise direction. This is clearly shown in the figure of the orbital diagram of chlorine(Cl).

## Chlorine(Cl) excited state electron configuration

Atoms can jump from one orbital to another orbital by excited state. This is called quantum jump. Ground state electron configuration of chlorine is 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5}. The valency of the element is determined by electron configuration in the excited state. The p-orbital has three sub-orbitals. The sub-orbitals are p_{x}, p_{y}, and p_{z}. Each sub-orbital can have a maximum of two electrons.

In the chlorine(Cl) ground-state electron configuration, the five electrons of the 3p orbital are located in the p_{x}, p_{y}, and p_{z} sub-orbitals. Then the correct electron configuration of chlorine(Cl) in ground state will be 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p_{x}^{2} 3p_{y}^{2} 3p_{z}^{1}. This electron configuration shows that the last shell of the chlorine atom has an unpaired electron(3p_{z}^{1}). So the valency of chlorine is 1.

When chlorine atoms are excited, then chlorine atoms absorb energy. As a result, an electron in the 3p_{y} sub-orbital jumps to the 3d_{xy} sub-orbital. The d-orbital has five sub-orbitals. The sub-orbitals are d_{xy}, d_{yz}, d_{zx}, d_{x2-y2} and d_{z2}. Each sub-orbital can have a maximum of two electrons. Therefore, the electron configuration of chlorine(Cl*) in excited state will be 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p_{x}^{2} 3p_{y}^{1} 3p_{z}^{1} 3d_{xy}^{1}. Here, chlorine has three unpaired electrons(3p_{y}^{1} 3p_{z}^{1} 3d_{xy}^{1}). Therefore, the valency of chlorine is 3.

When chlorine is further excited, then an electron in the 3p_{x} sub-orbital jumps to the 3d_{yz} sub-orbital. Therefore, the electron configuration of chlorine(Cl**) in excited state will be 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p_{x}^{1} 3p_{y}^{1} 3p_{z}^{1} 3d_{xy}^{1} 3d_{yz}^{1}. Here, chlorine has five unpaired electrons. Therefore, the valency of chlorine is 5.

When chlorine is further excited, then an electron in the 3s orbital jumps to the 3d_{zx} sub-orbital. The second orbit of the chlorine atom is filled with electrons. So the electron of the third orbit jumps and goes to another sub-orbital of the third orbit. Therefore, the electron configuration of chlorine(Cl***) in excited state will be 1s^{2} 2s^{2} 2p^{6} 3s^{1} 3p_{x}^{1} 3p_{y}^{1} 3p_{z}^{1} 3d_{xy}^{1} 3d_{yz}^{1} 3d_{zx}^{1}.

Here, chlorine has seven unpaired electrons. Therefore, the valency of chlorine is 7. From the above information, we can say that chlorine exhibits variable valency. Therefore, the valency of chlorine is 1, 3, 5, 7. Due to this, the oxidation states of chlorine are 1, 3, 5, 7.

## Chloride ion(Cl^{–}) electron configuration

After arranging the electrons, it is seen that the last shell of the chlorine(Cl) atom has seven electrons. In this case, the **valence electrons** of chlorine are seven. The elements that have 5, 6, or 7 electrons in the last shell receive the electrons in the last shell during bond formation. The elements that receive electrons and form bonds are called anions. That is, chlorine is an anion element.

Cl + e^{–} → Cl^{–}

During the formation of chlorine bonds, the last shell receives electrons and turns into a chloride ion(Cl^{–}). The electron configuration of chloride ion is 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6}. The electron configuration of chloride ion shows that chloride ion has three shells and the 3rd shell has eight electrons. The electron configuration shows that the chloride ion(Cl^{–}) has acquired the electron configuration of argon and it achieves a stable electron configuration.

## FAQs

How do you write the electron configuration for chlorine(Cl)?**Ans:** Chlorine(Cl) electron configuration is 1s^{2}2s^{2}2p^{6}3s^{2} 3p^{5}.

How many electrons does chlorine(Cl) have?**Ans: **17 electrons.

How many valence electrons does chlorine(Cl) have?**Ans:** Seven valence electrons.

What is the symbol for chlorine?**Ans:** The symbol for chlorine is ‘Cl’.

What is the valency of chlorine(Cl)?**Ans:** The valency of chlorine(Cl) is 1, 3, 5 and 7.

**Reference**