Magnesium (Mg) Electron Configuration

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Orbit Electron Configuration of Magnesium (Mg) atom is two electrons in first orbit (K), 8 electrons in second orbit (L) and 2 electron in third orbit (M)

Orbital Electron Configuration of Magnesium (Mg) atom is 1s2 2s2 2p6 3s2 which means Magnesium atom have two electrons inside 1s orbital, two electron in 2s orbital, 6 electrons in 2p orbitals and 2 electron in 3s orbitals

Also we can replace 1s2 2s2 2p6 with [Ne], therefore electron configuration of Magnesium (Mg) is [Ne] 3s2

Mg is the symbol for the element Magnesium, which is located in second group of the periodic table. Magnesium have total of twelve electrons in its atomic structure. Magnesium is 7th most common element on Earth and it makes up 2% of Earth’s crust.

Magnesium was first isolated in 1808 by Sir Humphry Davy who evaporated the mercury from magnesium amalgam made by electrolysing a mixture of moist magnesia and mercuric oxide.

The name magnesium comes from Magnesia, a district of Thessaly, Greece where the mineral magnesia alba was first found.

Magnesium is produced commercially through the electrolysis of molten magnesium chloride (MgCl2), which is derived primarily from seawater. Magnesium can also be produced through the direct reduction of its compounds with suitable reducing agents.

Magnesium is a silvery-white metal, it ignites quite quickly in air and burns with a bright light. When placed in air, magnesium tarnishes and form a thin oxide coating on its surface.

Some common uses of Magnesium are
– Car seats, luggage, laptops, cameras and power tools

– Used for purification of molten iron and steel

– Its used in flares, fireworks and sparklers

– A compound of magnesium with sulphur (Magnesium Sulphate) is used as mordant for dyes

– Another compound of magnesium, Magnesium Hydroxide is added to plastic for making it more fire retardant

– Magnesium oxide is used to make heat-resistant bricks for fireplaces and furnaces

– Magnesium compounds like magnesium hydroxide, magnesium sulphate, magnesium chloride and magnesium citrate is used in medicines

– Magnesium is also used in manufacturing of many other chemicals

Magnesium-centered porphyrin complexes are found in chlorophyll and are responsible for cholorphyll’s ability to absorb energy from sunlight.

Magnesium is essential for photosynthesis, and without it, life as we know it would not exist at all.

Magnesium is required for hundreds of enzymes in the human body to function properly. About 250–350 milligrammes of magnesium are consumed by the human body each day. Each of us has roughly 20 grams of magnesium, most of which is found in our bones.

Electron configuration refers to the arrangement of electrons in different orbits and orbitals of an atom in a certain order. Depending upon whether electrons are being arranged in Orbits or Orbitals there are two types of electron configurations – Orbit Electron Configuration and Orbital Electron Configuration.

In this article, I’ve discussed both Orbit and Orbital Electron Configurations of Magnesium (Mg) atom.

How do you write the electron configuration for Magnesium?

Magnesium atom in total twelve electrons, to write down the electron configuration of magnesium, the first two electrons would go into the 1s orbital. Because the 1s orbital can only accommodate two electrons, next two electrons are placed in the 2s orbital, next 6 electrons are placed in 2p orbital. The remaining two electrons would go in the 3s orbital. Putting all this together, electron configuration of magnesium is 1s2 2s2 2p5 3s2. Which can also be written as [Ne] 3s2 where [Ne] represents electron configuration of noble gas Neon.

Orbit Electron Configuration of Magnesium (Mg)

Niels Bohr, a Danish scientist, was the first to propose the concept of an orbit around an atom. In 1913, he presented a model of the atom to the scientific community. As per this model, the electrons in an atom follow a set path as they go around the nucleus in circular motion.

These set paths are called “Orbits” and are numbered as 1, 2, 3, ……… depending upon their closeness to nucleus of atom. So first circular path around nucleus is numbered as 1, second as 2 and so no. Moreover orbits are also denoted by English letters.

  • First orbit – K and have n = 1
  • Second orbit – L and have n = 2
  • Third orbit – M and have n = 3
  • Fourth orbit – N and have n = 4
  • and so on.

How many electrons any of these orbits can hold is determined by using formula 2n2 where n is number of orbit. Based upon this formula, different orbits in the atom can hold electrons as following.

  • First orbit – K (n = 1) can hold 2n2 = 2 (1)2 = 2 electrons
  • Second orbit – L and have n = 2 can hold 2n2 = 2 (2)2 = 2 (4) = 8 electrons
  • Third orbit – M and have n = 3 can hold 2n2 = 2 (3)2 = 2 (9) = 18 electrons
  • Fourth orbit – N and have n = 4 can hold 2n2 = 2 (4)2 = 2 (16) = 32 electrons
  • and so on.

As Magnesium atom have twelve electrons, therefore it’s Orbit Electron Configuration will be two electrons in K orbit, eight electrons in L orbit and two electrons in M orbit.

Electron Configuration of Magnesium (Mg) Atom showing 2, 8, 2 electrons in K, L, M shells

How many electron shells does Magnesium have?

Magnesium have electron configuration 2, 8, 2 which means it have 2 electrons in K shell, 8 electrons in L shell and 2 electron in M shell. Therefore Magnesium have 3 electron shells.

How many electrons does Magnesium have in K shell? (first shell)

2 electrons

How many electrons does Magnesium have in L shell? (second shell)

8 electrons

How many electrons does Magnesium have in M shell? (third shell)

2 electron

How many energy levels does Magnesium have?

Magnesium have electron configuration 2, 8, 2 which means it have 2 electrons in K shell, 8 electrons in L shell and 2 electron in M shell. Another name for shells is energy levels, because shells just represent different energy states of electrons, therefore in total magnesium have 3 energy levels which are K, L and M.

Orbital Electron Configuration of Magnesium (Mg)

Niels Bohr proposed the idea that electrons revolve around nucleus in specific circular paths called Orbits, but later on Heisenberg found out that it’s impossible to determine position and velocity of an electron inside the atom at same time, so how it’s possible that electrons do circular motion on specific paths in an atom.

In later years, Erwin Schrodinger developed a mathematical formula to compute the probability of finding the location of an electron inside an atom.

On the basis of this probability, the location of an electron inside an atom could be represented as the chances of that electron being located in a certain three-dimensional area surrounding the nucleus.

As 3D region can be explained only using 3 parameters, therefore in order to describe where an electron is? inside the atom.

We need three numbers – Principle Quantum Number (n), Angular Momentum Number (l) and Magnetic Momentum Number (m).

Therefore Orbits(this concept was proposed by Neils Bohr) are further divided into sub-energy levels called subshells. How many subshells an orbit have is equal to Principle Quantum Number (n) of orbit.

Therefore

  • First Orbit (K and n = 1) have 1 subshell
  • Second Orbit (L and n = 2) have 2 subshell
  • Third Orbit (M and n = 3) have 3 subshell
  • Fourth Orbit (N and n = 4) have 4 subshell

These sub-energy levels/subshells have specific regions where probability of finding electrons is maximum. These subshells are names as s, p, d, f and have angular momentum numbers as 0, 1, 2 and 3 respectively.

Which type of subshell an orbit have can be determined using Angular Momentum Number (I).
So
If Principle Quantum Number of an orbit is n
Then subshells in that orbit are 0 to (n – 1)

If
Angular Momentum Number(l) = 0 that means it’s s orbital
Angular Momentum Number(l) = 1 that means it’s p orbital
Angular Momentum Number(l) = 2 that means it’s d orbital
Angular Momentum Number(l) = 3 that means it’s f orbital

First Orbit (K and n = 1)
Angular Momentum Number (l) = 0 to (1 – 1) = 0 (0 to 0)
Which means first orbit just have one subshell which is s

Second Orbit (L and n = 2)
Angular Momentum Number (l) = 0 to (2 – 1) = 1 (0 to 1)
Which means second orbit have two subshells which are s and p

Third Orbit (M and n = 3)
Angular Momentum Number (l) = 0 to (3 – 1) = 2 (0 to 2)
Which means third orbit have three subshells (0, 1, 2) which are s, p and d

Fourth Orbit (N and n = 4)
Angular Momentum Number (l) = 0 to (4 – 1) = 3 (0 to 3)
Which means fourth orbit have four subshells (0, 1, 2, 3) which are s, p, d and f

OrbitPrinciple Quantum NumberNumber of SubshellsSubshells
First Orbit (K)n = 111s
Second Orbit (L)n = 222s
2p
Third Orbit (M)n = 333s
3p
3d
Fourth Orbit (N)n = 444s
4p
4d
4f

These s, p, d and f subshells further have subregions which are called Orbitals, orbitals are just regions inside a subshell where probability of existence of an electron is quite high.

How many orbitals a subshell have depends upon it’s Angular Momentum Number (l) and can be calculated using formula.
Number of orbitals in a subshell = 2l + 1 where I is Angular Momentum Number of a subshell.

Therefore
s subshell (Angular Momentum Number l = 0)
Number of orbitals = 2(0) + 1 = 1
So s subshell just have one orbital

p subshell (Angular Momentum Number l = 1)
Number of orbitals = 2(1) + 1 = 3
So p subshell have three orbitals

d subshell (Angular Momentum Number l = 2)
Number of orbitals = 2(2) + 1 = 4 + 1 = 5
so d subshell have five orbitals

f subshell (Angular Momentum Number l = 3)
Number of orbitals = 2(3) + 1 = 6 + 1 = 7
so f subshell have seven orbitals

Moreover electron holding capacity of a subshell can be calculated using formula
Number of electrons which a subshell can hold = 2(2I + 1) where I is Angular Momentum Number of subshell

Therefore
s subshell (Angular Momentum Number l = 0)
Number of electrons it can hold = 2(2(0) + 1) = 2(1) = 2
So s subshell can hold maximum two electrons

p subshell (Angular Momentum Number l = 1)
Number of electrons it can hold = 2(2(1) + 1) = 2(3) = 6
So p subshell can hold maximum six electrons

d subshell (Angular Momentum Number l = 2)
Number of electrons it can hold = 2(2(2) + 1) = 2(4 + 1) = 2(5) = 10
so d subshell can hold maximum ten electrons

f subshell (Angular Momentum Number l = 3)
Number of electrons it can hold = 2(2(3) + 1) = 2(6 + 1) = 2(7) = 14
so f subshell can hold maximum fourteen electrons

SubshellAngular Momentum Number (I)Number of Orbitals in
Subshell (2l + 1)
Maximum Electrons Subshell can hold 2(2l + 1)
s012
p136
d2510
f3714

Summarising all this we can write energy levels in an atom as

1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f 5g

But next question which arises is “in which order these orbitals should be filled in to figure out electron configuration of an atom?”.

Like should 2 electrons be filled in 1s orbital first or 3p orbital first???

Well answer to this question is Aufbau Principle.

According to the Aufbau Principle, in the ground state of an ion or an atom, electrons first occupy the atomic orbitals of lowest energy levels before filling up in higher energy levels. What this indicates is that the orbital with the lower energy will be filled first, followed by the orbital with the greater energy.

As per this principle energy of any orbital depends upon sum of Principle Quantum Number (n) and Angular Quantum Number (l).
Therefore
Energy of Orbital = n + l

So lower the value of n + l is lower its energy.

OrbitalnIEnergy (n + l)
1s101
2s202
2p213
3s303
3p314
3d326
4s404
4p415
4d426
4f437

From the above table its clear that 4s have less energy than 3d, so it should be filled first.
Based upon the energies of orbitals as per Aufbau Principle, order of filling of orbitals is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s and so on.

It’s tricky to remember what’s order of filling of orbitals as per Aufbau Principle, so you can use below diagram for easily filling up orbitals. Just follow the arrows from top right corner to bottom left corner diagonally.

Order of filling orbitals in an atom as per Aufbau Principle
Aufbau Principle Filling Of Orbitals Order

Order of filling of orbitals as per Aufbau Principle is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s and so on.

As Magnesium atom have 12 electrons, therefore it’s electron configuration is 1s2 2s2 2p6 3s2. Which means magnesium atom have 2 electrons each in its 1s, 2s orbitals, 6 electrons in 2p orbitals and 2 electron in 3s orbitals.

Electron Configuration of Magnesium (Mg) Atom showing 1s2 2s2 2p6 3s2
Magnesium (Mg)Electron Configuration
1s2 2s2 2p6 3s2

How many orbitals are in Magnesium Atom?

Electron Configuration of magnesium atom is 1s2 2s2 2p6 3s2 which means
Magnesium Atom have
– 2 electrons in 1s subshell
– 2 electrons in 2s subshell
– 6 electrons in 2p subshell
– 2 electron in 3s subshell

Distribution of electrons in orbitals of Magnesium Atom showing 2, 2, 6, 2 electrons in 1s, 2s, 2p, 3s

1s subshell have just one orbital
2s subshell also just have one orbital
2p subshell have 3 orbitals
3s subshell have 1 orbital

So in total magnesium atom 1 + 1 + 3 + 1 = 6 orbitals

Therefore magnesium atom have 6 orbitals.

From the above diagram showing distribution of electrons in orbitals of a magnesium atom, it’s clear that in total 6 orbitals are fully filled (these are 1s, 2s, 2p and 3s).

Does Magnesium have unpaired electrons?

From the above orbital diagram of electron configuration of magnesium its clear that all of its 12 electrons are in paired form in different orbitals 1s, 2s, 2p and 3s. Therefore magnesium doesn’t have unpaired electrons.

Does Magnesium have d orbitals?

Electron configuration of magnesium is 1s2 2s2 2p6 3s2
Therefore magnesium just have electrons in s, p orbitals and doesn’t have any d orbitals.

How many orbitals are in the third shell of a magnesium atom?

Electron configuration of magnesium is 1s2 2s2 2p6 3s2
From this electron configuration it’s clear that in third shell magnesium just have 2 electrons in 3s subshell. As Angular Momentum Number (l) of s subshell is zero which means it just have 1 orbital. Therefore there’s just one orbital in third shell of a magnesium atom.

Number of orbitals in a subshell can be figured out using formula – l to + l where l is Angular Momentum Number of subshell
For s subshell l = 0
For p subshell l = 1
For d subshell l = 2
For f subshell l = 3

Does Magnesium have stable Electron Configuration?

Electron Configuration of Magnesium is 1s2 2s2 2p6 3s2
This electron configuration is not stable, that’s why Magnesium easily loose its 2 electrons in 3s orbitals and become Mg2+ ion to achieve electron configuration of Noble Gas Neon (1s2 2s2 2p6).

Therefore Magnesium doesn’t have a stable electron configuration that’s why it tend to loose its 2 electrons and become magnesium ion (Mg2+).

How many electrons do Magnesium atoms need to loose to achieve stable electron configuration?

Electron Configuration of Magnesium is 1s2 2s2 2p6 3s2 to achieve more stable electron configuration of Neon gas (1s2 2s2 2p6). Magnesium atom need to loose 2 electrons in its 3s orbitals.

Valence Electrons of Magnesium (Mg)

Number of electrons in the last orbit of an element’s atom are called valence electrons.

As magnesium have electron configuration 1s2 2s2 2p6 3s2 so it’s last orbit is 3 (M shell which have Principle Quantum Number n = 3), as last orbit of magnesium have 2 electrons (in 3s orbital), therefore number of valence electrons in magnesium is two.

Magnesium2 valence electron

How many Valence Electrons does Magnesium have?

Magnesium have 2 valence electrons as it’s Orbital Electron Configuration is 1s2 2s2 2p6 3s2. As electron configuration shows, magnesium have 2 valence electron located in 3s subshell.

How many electrons does Magnesium have to loose to reach an octet?

Electron configuration of magnesium in terms of shells is 2, 8, 2 which means it have 2 electrons in K shell, 8 electrons in L shell and 2 electrons in M shell.

As there’s just two electrons in M shell therefore magnesium atom looses 2 electrons then it’s electron configuration become 2, 8 which is electron configuration of noble gas Neon and its more stable as compared to electron configuration of magnesium.

Therefore in order to reach an octet, magnesium need to loose 2 electrons.

Valency of Magnesium (Mg)

Valency refers to the ability of an element to combine with other elements. Valencies are same throughout the periodic table for elements that are located in the same group. 

Which means valency is same for all of Group 1 elements (K, Na etc. have valency = 1), Group 2 elements (Ca, Mg etc. have valency = 2) and so on for other groups in the periodic table. Also valency depends upon number of electrons that are found in an element’s outer most shell.

As Magnesium (Mg) have electron configuration 1s2 2s2 2p6 3s2 which means there are 2 electrons in outermost subshell. Therefore magnesium usually combines with atoms of other elements by just loosing these two electrons and forms mostly ionic compounds.

As magnesium achieves more stable electronic configuration of Neon noble gas (1s2 2s2 2p6) by loosing two electrons in its 3s subshell therefore valency of magnesium (Mg) is 2.

Magnesium (Mg)Valency = 2

Does Magnesium have Valency 1?

Valency refers to the ability of an element to combine with other elements and depends upon number of electrons available in outermost shell of atom.

Magnesium atom has three shells K, L and M.
Its electron configuration is 1s2 2s2 2p6 3s2 and therefore it can loose 2 electrons to achieve more stable electron configuration of nearest noble gas Neon (1s2 2s2 2p6). As magnesium just need to loose 2 electrons therefore its valency is 2 instead of 1.

Magnesium Ion (Mg2+) Electron Configuration

Above I discussed that in order to achieve stable electron configuration, in which all of orbitals are fully filled with electrons. Magnesium want to loose 1 electron in its 3s orbital and achieve electron configuration of Neon noble gas.

But when an atom of magnesium atom does loose 2 electrons, then number of protons(positive charge) and number of electrons(negative charge) becomes unequal.

Thus forming a Magnesium Ion (Mg2+). Which have 2 electron less than magnesium atom.

Mg → Mg2+ + 2e

Diagram showing formation of Magnesium Ion (Mg2+) from Magnesium atom

So Orbital Electron Configuration of Magnesium (Mg) atom is 1s2 2s2 2p6 3s2 and after loosing two electrons it becomes 1s2 2s2 2p6.
Therefore Electron Configuration of Magnesium (Mg2+) ion is 1s2 2s2 2p6. Which is same as electron configuration of noble gas Neon.

Diagram showing electron configuration of Magnesium (Mg2+) Ion - 1s2 2s2 2p6

How many electrons are in Magnesium ion Mg2+?

Magnesium ion (Mg2+) is formed when a magnesium atom looses two electrons. As magnesium atom in its ground state have in total 12 electrons and formation of magnesium ion require loosing of two electrons therefore total number of electron in magnesium ion are 10.

Is Magnesium electropositive?

Electropositive means tendency to loose electrons. As magnesium have electron configuration 1s2 2s2 2p6 3s2 therefore it quite easily looses two electrons in its 3s orbital and forms magnesium ion (Mg2+) thus achieving stable electron configuration of noble gas Neon. Therefore magnesium is a highly electropositive element.

Why Magnesium is a Reducing Agent?

A reducing agent is defined as a substance which loses electrons to other substances in a Redox Reaction and itself get oxidised to a higher valency state.

As magnesium have electron configuration 1s2 2s2 2p6 3s2 therefore it quite easily looses two electron in its 3s orbital and achieve stable electron configuration of noble gas Neon. As magnesium have strong tendency to loose electrons, therefore it act as Reducing Agent in Redox reactions.

Some examples of reactions in which magnesium is acting as a Reducing Agent are given below

Mg + Cl2 → MgCl2
In this reaction magnesium is loosing two electrons to chlorine atoms and its acting as a Reducing Agent.

2Mg + O2 2 MgO
In this reaction magnesium is loosing two electrons to oxygen atoms and its acting as a Reducing Agent.

Summary

Electron Configuration of Magnesium is 1s2 2s2 2p6 3s2
Electron Configuration of Magnesium Ion (Mg2+) is 1s2 2s2 2p6

FAQs

What is Valency of Magnesium?

Magnesium usually combines with other elements by loosing two electrons. Therefore magnesium looses two electrons form its 3s orbital and form magnesium ion (Mg2+) which have more stable electron configuration compared to magnesium atom’s electron configuration. Therefore valency of Magnesium (Mg) is 2.

What is electron configuration of neutral Magnesium?

Neutral Magnesium atom means that it have equal number of electrons and protons. As in neutral state Magnesium atom have total twelve electrons, therefore it’s electron configuration is 1s2 2s2 2p6 3s2. Which means magnesium atom have 2 electrons each in its 1s, 2s orbitals, 6 electrons in 2p orbitals and 2 electron in 3s orbital.

What is electron configuration of ground-state Magnesium atom?

Ground state atom means that all electrons inside it are in least possible energy state levels, therefore net total energy of atom in ground-state is minimum out of all possible states of it. As magnesium atom just have 12 electrons, therefore it’s electron configuration is 1s2 2s2 2p6 3s2. Which means magnesium atom have 2 electrons each in its 1s, 2s orbitals, 6 electrons in 2p orbitals and 2 electrons in 3s orbital.

What is electron configuration of Magnesium (Mg2+) ion?

When an atom of magnesium loose 2 electrons, then number of protons(positive charge) and number of electrons(negative charge) becomes unequal. Thus forming a Magnesium Ion (Mg2+). As electron configuration of Magnesium atom is 1s2 2s2 2p6 3s2 and formation of magnesium ion (Mg2+) require loosing of 2 electrons therefore electron configuration of magnesium ion is 1s2 2s2 2p6.

Which element have electron configuration 1s2 2s2 2p6 3s2 ?

Magnesium (Mg)

In what type of orbital is the outermost electron in Mg?

Electron configuration of magnesium is 1s2 2s2 2p6 3s1
From this it can be clearly observed that outermost electron in magnesium atom is present in 3s orbital.

Some Properties of Magnesium

Element NameMagnesium
SymbolMg
Atomic Number12
Number of electrons12
Group in Periodic Table2
Atomic Weight24.305 u
Number of Valence Electrons2
Valency2
Oxidation States+ 2
Melting Point650 °C (923.2 K)
Boiling Point1091 °C (1364 K)
Atomic Radius173 picometre
Electronegativity1.31 on Pauling Scale
Van der waals Radius173 picometre
Covalent Radius139 picometre
(single bond radius)
Electron Affinity– 0.4 eV
Density1.738 g/cm3
First Ionisation Energy737.7 kJ/mol
Second Ionisation Energy1450.7 kJ/mol
Third Ionisation Energy7732.7 kJ/mol

Some Uses of Magnesium

Magnesium is used in making car seats, luggage, laptops, cameras and power tools
Used for purification of molten iron and steel
Its used in flares, fireworks and sparklers
A compound of magnesium with sulphur (Magnesium Sulphate) is used as mordant for dyes
Another compound of magnesium, Magnesium Hydroxide is added to plastic for making it more fire retardant
Magnesium oxide is used to make heat-resistant bricks for fireplaces and furnaces
Magnesium compounds like magnesium hydroxide, magnesium sulphate, magnesium chloride and magnesium citrate is used in medicines
Magnesium is also used in manufacturing of many other chemicals

Physical Properties of Magnesium

Magnesium is a silvery-white metal, it ignites quite quickly in air and burns with a bright light
When placed in air, magnesium tarnishes and form a thin oxide coating on its surface

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