Complete Electron Configuration for Chlorine (Cl, Cl-) (2023)

Chlorine is the 17th element in the periodic table and its symbol is ‘Cl’. In this article, I have discussed in detail how to easily write the complete electron configuration of chlorine.

What is the electron configuration of chlorine?

The total number ofelectrons in chlorineis seventeen. These electrons are arranged according to specific rules in different orbitals.

The arrangement of electrons in chlorine in specific rules in different orbits and orbitals is called theelectron configurationof chlorine.

The electron configuration of chlorine is 1s²2s²2p⁶3s²3p⁵,if the electron arrangement is through orbitals. Electron configuration can be done in two ways.

• Electron configuration through orbit (Bohr principle)
• Electron configuration through orbital (Aufbau principle)

Electron configuration through orbitals follows different principles. For example Aufbau principle, Hund’s principle, and Pauli’s exclusion principle.

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, and N is the name of the fourth orbit. The electron holding capacity of each orbit is 2n².

For example,

1. n = 1 for K orbit.
   The maximum electron holding capacity in K orbit is 2n²= 2 × 1²= 2.
2. For L orbit, n = 2.
   The maximum electron holding capacity in L orbit is 2n²= 2 × 2²= 8.
3. n=3 for M orbit.
   The maximum electrons holding capacity in M orbit is 2n²= 2 × 3²= 18.
4. n=4 for N orbit.
   The maximum electrons holding capacity in N orbit is 2n²= 2 × 4²= 32.

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 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.

For example,

• 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.

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 thatthe 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.

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.

The method of entering electrons into orbitals through the Aufbau principle 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 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 complete electron configuration will be 1s² 2s² 2p⁶ 3s² 3p⁵.

Note:The abbreviated electron configuration of chlorine is [Ne] 3s²3p⁵. 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 quantum jump.

The ground state electron configuration of chlorine is 1s² 2s² 2p⁶ 3s² 3p⁵. We already know that the p-subshell has three orbitals. The orbitals are p_x, p_y, and p_zand 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 1s² 2s² 2p⁶ 3s² 3p_x² 3p_y² 3p_z¹.

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 1s² 2s² 2p⁶ 3s² 3p_x² 3p_y¹ 3p_z¹ 3d_xy¹.

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 1s² 2s² 2p⁶ 3s² 3p_x¹ 3p_y¹ 3p_z¹ 3d_xy¹ 3d_yz¹. 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 1s² 2s² 2p⁶ 3s¹ 3p_x¹ 3p_y¹ 3p_z¹ 3d_xy¹ 3d_yz¹ 3d_zx¹. 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 1s² 2s² 2p⁶ 3s² 3p⁶. 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.

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