# How to Write the Electron Configuration for Chlorine (Cl)?

Chlorine is the 17th element in the periodic table and the symbol is ‘Cl’. Chlorine has an atomic number of 17, which means that its atom has seventeen electrons around its nucleus.

**To write the electron configuration for chlorine, the first two electrons enter the 1s orbital. Since the 1s orbital can hold only two electrons the next two enter the 2s orbital. The next six electrons enter the 2p subshell. The p subshell can hold a maximum of six electrons. Hence, the next two electrons enter the 3s orbital. Since the 3s orbital is now full, the remaining five electrons move into the 3p subshell. Therefore, the electron configuration of chlorine will be 1s ^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5}.**

The electron configuration of chlorine refers to the arrangement of electrons in the chlorine atom’s orbitals. It describes how electrons are distributed among the various atomic orbitals and energy levels, and provides a detailed map of where each electron is likely to be found.

To understand the mechanism of chlorine electron configuration, you need to understand two basic things. These are orbits and orbitals. Also, you can arrange electrons in those two ways. In this article, I have discussed all the necessary points to understand the mechanism of chlorine electron configuration. I hope this will be helpful in your study.

## Electron arrangement of Chlorine 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 and provided a complete idea of orbit in that model.

The electrons of the atom revolve around the nucleus in a certain circular path. These circular paths are called orbits (shells or energy levels). These orbits are expressed by n. [n = 1,2,3,4 . . . The serial number of the orbit]

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

Shell Number (n) | Shell Name | Electrons Holding Capacity (2n^{2}) |

1 | K | 2 |

2 | L | 8 |

3 | M | 18 |

4 | N | 32 |

### Explanation:

- Let, n = 1 for K orbit. So, the maximum electron holding capacity in the K orbit is 2n
^{2}= 2 × 1^{2}= 2 electrons. - n = 2, for L orbit. The maximum electron holding capacity in the L orbit is 2n
^{2}= 2 × 2^{2}= 8 electrons. - n=3 for M orbit. The maximum electron holding capacity in the 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 atom is 2, 8, 7.

The Bohr atomic model has many limitations. In the Bohr atomic model, the electrons can only be arranged in different shells but the exact position, orbital shape, and spin of the electron cannot be determined.

Also, electrons can be arranged correctly from 1 to 18 elements. The electron arrangement of any element with atomic number greater than 18 cannot be accurately determined by the Bohr atomic model following the 2n^{2} formula. We can overcome all limitations of the Bohr model following the electron configuration through orbital.

## Electron configuration of Chlorine through orbital

Atomic energy shells are subdivided into sub-energy levels. These sub-energy levels are also called orbital. The most probable region of electron rotation around the nucleus is called the orbital.

The sub-energy levels depend on the azimuthal quantum number. It is expressed by ‘l’. The value of ‘l’ is from 0 to (n – 1). The sub-energy levels are known as s, p, d, and f.

Orbit Number | Value of ‘l’ | Number of subshells | Number of orbitals | Subshell name | Electrons holding capacity | Electron configuration |

1 | 0 | 1 | 1 | 1s | 2 | 1s^{2} |

2 | 0 1 | 2 | 1 3 | 2s 2p | 2 6 | 2s^{2} 2p^{6} |

3 | 0 1 2 | 3 | 1 3 5 | 3s 3p 3d | 2 6 10 | 3s^{2} 3p^{6} 3d^{10} |

4 | 0 1 2 3 | 4 | 1 3 5 7 | 4s 4p 4d 4f | 2 6 10 14 | 4s^{2} 4p^{6} 4d^{10} 4f^{14} |

### Explanation:

- If n = 1,

(n – 1) = (1–1) = 0

Therefore, the value of ‘l’ is 0. So, the sub-energy level is 1s. - If n = 2,

(n – 1) = (2–1) = 1.

Therefore, the value of ‘l’ is 0, 1. So, the sub-energy levels are 2s, and 2p. - If n = 3,

(n – 1) = (3–1) = 2.

Therefore, the value of ‘l’ is 0, 1, 2. So, the sub-energy levels are 3s, 3p, and 3d. - If n = 4,

(n – 1) = (4–1) = 3

Therefore, the value of ‘l’ is 0, 1, 2, 3. So, the sub-energy levels are 4s, 4p, 4d, and 4f. - If n = 5,

(n – 1) = (n – 5) = 4.

Therefore, l = 0,1,2,3,4. The number of sub-shells will be 5 but 4s, 4p, 4d, and 4f in these four subshells it is possible to arrange the electrons of all the elements of the periodic table.

Sub-shell name | Name source | Value of ‘l’ | Value of ‘m’(0 to ± l) | Number of orbital (2l+1) | Electrons holding capacity2(2l+1) |

s | Sharp | 0 | 0 | 1 | 2 |

p | Principal | 1 | −1, 0, +1 | 3 | 6 |

d | Diffuse | 2 | −2, −1, 0, +1, +2 | 5 | 10 |

f | Fundamental | 3 | −3, −2, −1, 0, +1, +2, +3 | 7 | 14 |

The orbital number of the s-subshell is one, three in the p-subshell, five in the d-subshell, and seven in the f-subshell. Each orbital can have a maximum of two electrons.

The sub-energy level ‘s’ can hold a maximum of two electrons, ‘p’ can hold a maximum of six electrons, ‘d’ can hold a maximum of ten electrons, and ‘f’ can hold a maximum of fourteen electrons.

Aufbau is a German word, which means building up. The main proponents of this principle are scientists Niels Bohr and Pauli. The Aufbau method is to do electron configuration through the sub-energy level.

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.

The energy of an orbital is calculated from the value of the principal quantum number ‘n’ and the azimuthal quantum number ‘l’. The orbital for which the value of (n + l) is lower is the low energy orbital and the electron will enter that orbital first.

Orbital | Orbit (n) | Azimuthal quantum number (l) | Orbital energy (n + l) |

3d | 3 | 2 | 5 |

4s | 4 | 0 | 4 |

Here, the energy of 4s orbital is less than that of 3d. So, the electron will enter the 4s orbital first and enter the 3d orbital when the 4s orbital is full.

Following the Aufbau principle, the sequence of entry of electrons into orbitals is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p.

So, In writing the electron configuration for chlorine, the first two electrons of chlorine enter the 1s orbital. As you already know, the s-subshell can have a maximum of two electrons. Therefore, the next two electrons enter the 2s orbital. Also, you know that the p-subshell can have a maximum of six electrons. So, the next six electrons enter the 2p subshell.

The second orbit is now full. So, the remaining electrons will enter the third orbit. Then the next two electrons will enter the 3s orbital and the remaining five electrons will enter the 3p subshell. Therefore, the complete electron configuration of chlorine will be 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5}.

Note:The abbreviated electron configuration of chlorine is [Ne] 3s^{2}3p^{5}. When writing an electron configuration, you have to write serially.

## Electron configuration of chlorine in the excited state

Atoms can jump from one orbital to another orbital in the excited state. This is called a quantum jump. The ground state electron configuration of chlorine is 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5}. We already know that the p-subshell has three orbitals. The orbitals are p_{x}, p_{y}, and p_{z} and each orbital can have a maximum of two electrons.

In the chlorine ground-state electron configuration, the five electrons of the 3p orbital are located in the p_{x}(2), p_{y}(2), and p_{z}(1) orbitals. Then the correct electron configuration of chlorine in the 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. 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} orbital jumps to the 3d_{xy} orbital.

We already know that the d-subshell has five orbitals. The orbitals are d_{xy}, d_{yz}, d_{zx}, d_{x2-y2} and d_{z2} and each orbital can have a maximum of two electrons. So, the electron configuration of chlorine(Cl*) in an excited state will be 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p_{x}^{2} 3p_{y}^{1} 3p_{z}^{1} 3d_{xy}^{1}.

The valency of the element is determined by electron configuration in the excited state. Here, chlorine has three unpaired electrons. Therefore, the valency of chlorine is 3. When chlorine is further excited, then an electron in the 3p_{x} orbital jumps to the 3d_{yz} orbital.

Therefore, the electron configuration of chlorine(Cl**) in an 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} orbital. The second orbit of the chlorine atom is filled with electrons. So the electron of the third orbit jumps and goes to another 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, and 7. Due to this, the oxidation states of chlorine are +7, +5, +1, and -1.

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

After arranging the electrons, it is seen that the last shell of the chlorine atom has seven electrons. Therefore, 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.

During the formation of chlorine bonds, the last shell receives an electron and turns into a chloride ion(Cl^{–}). The elements that receive electrons and form bonds are called anion. That is, chlorine is an anion element.

Cl + e^{–} → Cl^{–}

The electron configuration of chloride ion(Cl^{–}) is 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6}. This electron configuration shows that the 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 complete electron configuration for chlorine?

**Ans:**The complete electron configuration for chlorine is 1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}.### What is the valency of chlorine?

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

The electronic configuration of a chlorine atom (Cl) is 1s

^{2}2s^{2}2p^{6}3s^{2}3p^{5}. It has 17 electrons, with two in the 1s orbital, two in the 2s orbital, six in the 2p orbital, two in the 3s orbital, and five in the 3p orbital.### What is the configuration of the chlorine ion(Cl

^{–})?The electron configuration of chloride ion(Cl

^{–}) is 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}. This electron configuration shows that the chloride ion has three shells and the 3rd shell has eight electrons.### What is the electronic structure of chlorine?

The electronic structure of chlorine is 2, 8, 7. This indicates that chlorine has two electrons in its innermost energy level (the first shell), eight electrons in the second energy level (the second shell), and seven electrons in the outermost energy level (the third shell).

### What is the ground-state electron configuration of the chloride ion (Cl−)?

The ground-state electron configuration of the chloride ion (Cl−) is 1s

^{2}2s^{2}2p^{6}3s^{2}3p_{x}^{2}3p_{y}^{2}3p_{z}^{2}.### What is the abbreviated electron configuration of chlorine?

The abbreviated electron configuration of chlorine is [Ne] 3s

^{2}3p^{5}.### What is the ground state electron configuration of chlorine?

The ground state electron configuration of chlorine is 1s

^{2}2s^{2}2p^{6}3s^{2}3p_{x}^{2}3p_{y}^{2}3p_{z}^{1}.### How many energy levels does chlorine have?

Chlorine (Cl) has three energy levels. The first energy level can hold a maximum of 2 electrons, the second energy level can hold a maximum of 8 electrons, and the third energy level can hold a maximum of 18 electrons.