Chlorine Electron Configuration and Atomic Orbital Diagram
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.
The electron configuration of chlorine is 1s2 2s2 2p6 3s2 3p5 which means that 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 1s2 2s2 2p6 3s2 3p5.
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 and chloride(Cl⁻) electron configuration, valency and valence electrons and ground and excited state electron configuration of chlorine. I hope this will be helpful in your study.
Electron arrangement of Chlorine through Bohr Model
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 2n2.
| Shell Number (n) | Shell Name | Electrons Holding Capacity (2n2) |
| 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 2n2 = 2 × 12 = 2 electrons.
- n = 2, for L orbit. The maximum electron holding capacity in the L orbit is 2n2 = 2 × 22 = 8 electrons.
- n=3 for M orbit. The maximum electron holding capacity in the M orbit is 2n2 = 2 × 32 = 18 electrons.
- n=4 for N orbit. The maximum electron holding capacity in N orbit is 2n2 = 2 × 42 = 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 2n2 formula. We can overcome all limitations of the Bohr model following the electron configuration through orbital.
Electron configuration of Chlorine through Aufbau Model
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 | 1s2 |
| 2 | 0 1 | 2 | 1 3 | 2s 2p | 2 6 | 2s2 2p6 |
| 3 | 0 1 2 | 3 | 1 3 5 | 3s 3p 3d | 2 6 10 | 3s2 3p6 3d10 |
| 4 | 0 1 2 3 | 4 | 1 3 5 7 | 4s 4p 4d 4f | 2 6 10 14 | 4s2 4p6 4d10 4f14 |
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 capacity 2(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.
Therefore, the complete electron configuration for chlorine should be written as 1s2 2s2 2p6 3s2 3p5.
Note: The abbreviated electron configuration of chlorine is [Ne] 3s2 3p5. When writing an electron configuration, you have to write serially.
How to write the orbital diagram for chlorine?
Orbital diagrams are usually represented by boxes. Each box represents an orbital and the arrows within the box represent the position of the electron. The boxes are arranged in order of energy of the orbitals.
The lowest energy orbitals are closest to the nucleus and the higher energy orbitals are progressively further away from the nucleus in order of their energy levels. To write the orbital diagram of chlorine, you have to write the orbital notation of chlorine. Which has been discussed in detail above.
1s is the closest and lowest energy orbital to the nucleus. Therefore, the electrons will first enter the 1s orbital. According to Hund’s principle, the first electron will enter 1s orbital 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 2p orbital is now full. Then the next two electrons will enter the 3s orbital just like the 1s orbital. Then 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.
Try the Orbital Diagram Calculator and get instant results for any element.
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 1s2 2s2 2p6 3s2 3p5. We already know that the p-subshell has three orbitals. The orbitals are px, py, and pz 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 px(2), py(2), and pz(1) orbitals. Then the correct electron configuration of chlorine in the ground state will be 1s2 2s2 2p6 3s2 3px2 3py2 3pz1.
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 3py orbital jumps to the 3dxy orbital.
We already know that the d-subshell has five orbitals. The orbitals are dxy, dyz, dzx, dx2-y2 and dz2 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 3px2 3py1 3pz1 3dxy1.
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 3px orbital jumps to the 3dyz orbital.
Therefore, the electron configuration of chlorine(Cl**) in an excited state will be 1s2 2s2 2p6 3s2 3px1 3py1 3pz1 3dxy1 3dyz1. 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 3dzx 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 3px1 3py1 3pz1 3dxy1 3dyz1 3dzx1. 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.
This was such a clear and informative post! The detailed explanation of chlorine’s electron configuration and the accompanying atomic orbital diagram really helped me visualize the concept. I appreciate the use of visuals to enhance understanding. Thank you for breaking it down so nicely!
This post really helped me understand chlorine’s electron configuration and how it fits into the periodic table! The diagrams made it so much easier to visualize the atomic orbitals. Thanks for breaking it down so clearly!
This is a fantastic explanation of chlorine’s electron configuration! The diagrams really help in visualizing how the electrons are arranged in atomic orbitals. I appreciated how you broke down the concepts step by step. Thank you for making a complex topic so accessible!
Great explanation of chlorine’s electron configuration! I found the atomic orbital diagram really helpful in visualizing how the electrons are arranged. It makes understanding its reactivity so much easier. Thanks for breaking it down!
This post explains chlorine’s 1s, 2s, 2p, and 3p5 configuration very well. The atomic number 17 breakdown is clear. Looking at these diagrams reminds me of grid-based design. I use a pixel bead tool to plan projects where pieces fit specific spots, similar to electron placement logic. Having a structured approach helps in both chemistry and creative work. Thanks for the clear guide!