Electron Configuration for Magnesium (Mg, Mg2+ ion)
Magnesium is the 12th element in the periodic table and its symbol is ‘Mg’. In this article, I have discussed in detail how to easily write the complete electron configuration of magnesium.
What is the electron configuration of magnesium?
The total number of electrons in magnesium is twelve. These electrons are arranged according to specific rules in different orbitals.
The arrangement of electrons in magnesium in specific rules in different orbits and orbitals is called the electron configuration of magnesium.
The electron configuration of magnesium is [Ne] 3s^{2}, 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 2n^{2}.
Shell Number (n)  Shell Name  Electrons Holding Capacity (2n^{2}) 
1  K  2 
2  L  8 
3  M  18 
4  N  32 
For example,
 n = 1 for K orbit.
The maximum electron holding capacity in K orbit is 2n^{2} = 2 × 1^{2} = 2.  For L orbit, n = 2.
The maximum electron holding capacity in L orbit is 2n^{2} = 2 × 2^{2} = 8.  n=3 for M orbit.
The maximum electrons holding capacity in M orbit is 2n^{2} = 2 × 3^{2 }= 18.  n=4 for N orbit.
The maximum electrons holding capacity in N orbit is 2n^{2} = 2 × 4^{2} = 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 magnesium is 12. That is, the number of electrons in magnesium is twelve. Therefore, the magnesium atom will have two electrons in the first shell, eight in the 2nd orbit, and two electrons in the 3rd shell.
Therefore, the order of the number of electrons in each shell of a magnesium(Mg) atom is 2, 8, 2. 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 model. The electron configuration of all the elements can be done through orbital diagrams.
Electron configuration through orbital
Atomic energy shells are subdivided into subenergy levels. These subenergy levels are also called orbital. The most probable region of electron rotation around the nucleus is called the orbital.
The subenergy levels depend on the azimuthal quantum number. It is expressed by ‘l’. The value of ‘l’ is from 0 to (n – 1). The subenergy levels are known as s, p, d, and f.
Orbit Number  Value of ‘l’  Number of subshells  Number of orbital  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} 
For example,
 If n = 1,
(n – 1) = (1–1) = 0
Therefore, the value of ‘l’ is 0. So, the subenergy level is 1s.  If n = 2,
(n – 1) = (2–1) = 1.
Therefore, the value of ‘l’ is 0, 1. So, the subenergy levels are 2s, and 2p.  If n = 3,
(n – 1) = (3–1) = 2.
Therefore, the value of ‘l’ is 0, 1, 2. So, the subenergy 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 subenergy 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 subshells 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.
Subshell 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 ssubshell is one, three in the psubshell, five in the dsubshell and seven in the fsubshell. Each orbital can have a maximum of two electrons.
The subenergy 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 subenergy 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.
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 magnesium enter the 1s orbital. The sorbital can have a maximum of two electrons. Therefore, the next two electrons enter the 2s orbital. The porbital can have a maximum of six electrons.
So, the next six electrons enter the 2p orbital and the remaining two electrons enter the 3sorbital. Therefore, the magnesium complete electron configuration will be 1s^{2} 2s^{2} 2p^{6} 3s^{2}.
Note: The unabbreviated electron configuration of magnesium is [Ne] 3s^{2}. When writing an electron configuration, you have to write serially.
Video for Magnesium Electron Configuration
Magnesium ion(Mg^{2+}) Electron configuration
The ground state electron configuration of magnesium is 1s^{2} 2s^{2} 2p^{6} 3s^{2}. After the electron configuration, the last shell of the magnesium atom has two electrons. Therefore, the valency and valence electrons of magnesium are 2.
The elements that have 1, 2, or 3 electrons in the last shell donate the electrons in the last shell during bond formation. Magnesium donates the electron of the last shell to form bonds and turns into a magnesium ion(Mg^{+2}).
The elements that form bonds by donating electrons are called cations. That is, magnesium is a cation element.
Mg – 2e^{–} → Mg^{2+}
The electron configuration of magnesium ion(Mg^{+2}) is 1s^{2} 2s^{2} 2p^{6}. This electron configuration shows that magnesium ion(Mg^{+2}) has acquired the electron configuration of neon and it achieves an octave full stable electron configuration.
FAQs

How do you write the complete electron configuration for magnesium?
The complete electron configuration for magnesium is 1s^{2} 2s^{2} 2p^{6} 3s^{2}.

What is the electron configuration for mg2+?
The electron configuration of magnesium ion(Mg^{+2}) is 1s^{2} 2s^{2} 2p^{6}. This electron configuration shows that magnesium ion(Mg^{+2}) has acquired the electron configuration of neon and it achieves an octave full stable electron configuration.

What is the valence electron configuration for the magnesium atom?
The valence electron configuration for the magnesium atom is [Ne] 3s^{2}.

What is the complete ground state electron configuration for the magnesium atom?
The complete ground state electron configuration for the magnesium atom is 1s^{2} 2s^{2} 2p^{6} 3s^{2}.

How many completely filled s orbitals does magnesium have?
Magnesium (Mg) has three completely filled s orbital. The s orbitals can hold a maximum of 2 electrons, and the electron configuration of magnesium is 1s^{2} 2s^{2} 2p^{6} 3s^{2}. This means that the 1s orbital is completely filled with 2 electrons, while the 2s and 3s orbital are also completely filled with 2 electrons. Therefore, magnesium has three completely filled s orbital.

What is the abbreviated electron configuration for magnesium?
The abbreviated electron configuration for magnesium is [Ne] 3s^{2}. The noble gas neon (Ne) has the electron configuration 1s^{2} 2s^{2} 2p^{6}, which represents the completely filled inner energy levels. By using the noble gas notation, we can replace this inner electron configuration of neon with the symbol [Ne].

How many electron shells does magnesium have?
Magnesium has 3 electron shells. The electron configuration of magnesium is 1s^{2} 2s^{2} 2p^{6} 3s^{2}. From this configuration, we can see that there are electrons present in the first, second, and third energy levels (shells). Therefore, magnesium has a total of 3 electron shells.

How many electrons are in the outer orbit of magnesium?
Magnesium (Mg) has 2 electrons in its outer orbit. The outer orbit refers to the outermost energy level, which is the third energy level (designated as the 3s orbital) in the electron configuration of magnesium. In this case, there are 2 electrons in the 3s orbital, which are the valence electrons.

How many electrons are in the 3s sublevel for magnesium?
The 3s sublevel of magnesium (Mg) contains 2 electrons.

How many electrons are in the n = 2 shell of a magnesium atom?
The second energy level can hold a maximum of 8 electrons. The electron configuration of magnesium is 1s^{2} 2s^{2} 2p^{6} 3s^{2}. From this configuration, we can see that there are a total of 8 electrons in the n = 2 shell. This includes the 2 electrons in the 2s sublevel and the 6 electrons in the 2p sublevel. Therefore, the n = 2 shell of a magnesium atom contains 8 electrons.

How many electrons are in the n = 3 shell of a magnesium ion (Mg^{2+})?
The n = 3 shell of the Mg^{2+} ion does not contain any electrons. When magnesium loses two electrons to form the Mg^{2+} ion, it achieves a stable, noble gaslike configuration similar to neon (Ne). Therefore, the Mg^{2+} ion has the electron configuration of [Ne], representing a completely filled n = 2 shell.

What is the symbol for magnesium ion?
The symbol for the magnesium ion with a 2+ charge is Mg^{2+}. The 2+ indicates that the magnesium ion has lost two electrons, resulting in a 2+ charge.