Carbon (C) Electron Configuration

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Orbit Electron Configuration of Carbon (C) atom is two electrons in first orbit (K) and 4 electrons in second orbit (L)

Orbital Electron Configuration of Carbon (C) atom is 1s2 2s2 2p2 which means Carbon atom have two electrons inside 1s orbital, two electron in 2s orbital and 2 electrons in 2p orbital

Also we can replace 1s2 with [He], therefore electron configuration of Carbon (C) is [He] 2s2 2p2

C is the symbol for the element Carbon, which is located at position six of the periodic table. Carbon have total of six electrons in its atomic structure. Carbon is quite unique element as its foundation of human life, moreover its found in almost every organic compound.

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 Carbon (C) atom.

Orbit Electron Configuration of Carbon (C)

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 Carbon atom have six electrons, therefore it’s Orbit Electron Configuration will be two electrons in K orbit and four electrons in L orbit.

Orbit Electronic Configuration of Carbon showing 2 electrons in K shell and 4 electrons in L shell

How many electron shells does Carbon have?

Carbon have electron configuration 2, 4 which means it have 2 electrons in K shell and 4 electrons in L shell. Therefore Carbon have 2 electron shells.

Orbital Electron Configuration of Carbon (C)

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 Carbon atom have six electrons, therefore it’s electron configuration is 1s2 2s2 2p2. Which means Carbon atom have 2 electrons each in its 1s, 2s, 2p orbitals.

Orbital Electronic Configuration of Carbon C showing 1s2 2s2 2p2
CarbonElectron Configuration
1s2 2s2 2p2

Valence Electrons of Carbon (C)

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

As Carbon have electron configuration 1s2 2s2 2p2 so it’s last orbit is 2 (L shell which have Principle Quantum Number n = 2), as last orbit of Carbon have 4 total electrons (2 in 2s and 2 in 2p subshell), therefore number of valence electrons in Carbon are four.

Carbon (C)4 valence electron

How many Valence Electrons does Carbon have?

Carbon have 4 electrons as it’s Orbital Electron Configuration is 1s1 2s2 2p2. As electron configuration shows, Carbon have 4 valence electrons which are located in 2s and 2p subshells.

Valency of Carbon (C)

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 Carbon (C) have electron configuration 1s2 2s2 2p2, which means there are in total four electrons in 2s and 2p subshells.

Therefore C atom is not stable (there can be six electrons in 2p subshell but Carbon just have 2 electrons in this subshell)
So in order to become stable, Carbon usually share electrons with other elements atoms and form bonds called covalent bonds (sharing pairs of electrons)

As there are four electrons in outermost shell of Carbon, therefore it forms four covalent bonds and achieve electron configuration of noble gas Neon to become stable.

Therefore valency of Carbon (C) is four.

Carbon (C)Valency = 4

So valency of Carbon is four, it’s also called as Tetravalency of carbon. Also many of physical and chemical properties of carbon can be explained based upon the fact that it have valency 4.

Properties of Carbon based upon its Tetravalency

  • Because of its tetravalency and relatively tiny size, carbon shows significant catenation.
    Carbon is able to create several strong bonds with other elements, particularly hydrogen, due to the fact that it is tetravalent and has a tiny size.
  • The tetravalency of carbon is what makes diamond, an allotrope of carbon, the hardest naturally occuring solid. 

Does Carbon have Valency 2?

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

Valency is basically defined by this gain or loss of electrons from an atom or element. If we want to calculate the valency then we need to actually see the electrons lost, gained or shared and the bonds formed by the element whose valency we want to calculate.

In CO carbon has a valency of 2. This is because carbon shares its two electrons with oxygen and oxygen in turn share its two electrons with carbon. As a result, both carbon and oxygen complete their octet and the compound carbon monoxide formed is stable.

Carbide (C4-) ion Electron Configuration

The electron configuration of carbon shows that the outermost shell of carbon atoms contains four electrons. As a result, the number of valence electrons that carbon has is four.

But as outmost shell of carbon atom is L shell, which can contain 8 electrons in total, but in case of carbon atom this shell just have 4 electrons.
Therefore, the last carbon shell gains four more electrons and changes into a carbide ion (C4-).

C + 4e → C4-

So Orbital Electron Configuration of Carbon (C) atom is 1s2 2s2 2p2 and after gaining four electrons it becomes 1s2 2s2 2p6.
Therefore Electron Configuration of Carbide ion (C4-) ion is 1s2 2s2 2p6.

Why Carbon can neither form C4+ nor C4- ion?

The removal of all four electron elections from a carbon atom would take a significant amount of energy, which prevents carbon from forming the C4+ cation.

Because the nucleus of carbon has only six protons, it is not possible for it to form the C4- anion because it would be impossible for it to hold on to 10 electrons.

Carbon doesn’t form ions then how it react with other elements?

Electron Configuration of Carbon is 1s2 2s2 2p2 and due to extensive amount of energy needed to remove four electrons, it doesn’t form C4+ cation. Similarly due to the fact that carbon atom just have six protons, it cannot hold onto 10 electrons and form C4- anion.

So Carbon doesn’t react with other elements by either gain or loosing electrons. Rather it reacts with other atoms by sharing electrons and forming covalent bonds.

For example in case of Methane (CH4) carbon shares its 4 valence electrons with each of four hydrogen atoms, therefore it will have 8 electrons in total in it’s outmost shell.

Properties of Carbon

Element NameCarnon
SymbolC
Atomic Number6
Number of electrons6
Group in Periodic Table16
Atomic Weight12.011 u
Number of Valence Electrons4
Valency4
First Ionisation Energy1086.5 kJ/mol
Second Ionisation Energy2352.6 kJ/mol
Third Ionisation Energy4620.5 kJ/mol
Oxidation States– 4, 2, 4
Atomic Radius67 picometre
Electronegativity2.55 on Pauling Scale

FAQs

What is Valency of Carbon in CCL4?

4

What is Valency of Carbon in CO2?

4

What is electron configuration of neutral Carbon?

Neutral carbon atom means that it have equal number of electrons and protons. As in neutral state carbon atom have total six electrons, therefore it’s electron configuration is 1s2 2s2 2p2. Which means carbon atom have 2 electrons each in its 1s, 2s orbitals and 2 electrons in 2p orbitals.

What is electron configuration of ground-state carbon 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 carbon atom just have 6 electrons, therefore it’s electron configuration is 1s2 2s2 2p2. Which means carbon atom have 2 electrons each in its 1s, 2s orbitals, 2 electrons in 2p orbitals.

How many unpaired electrons are there in Carbon atom?

Electron configuration of carbon atom is 1s2 2s2 2p2
1s subshell is fully filled and have paired electrons
2s subshell is also fully filled and have paired electron
2p subshell is not fully filled, it just have 2 electrons which are present in different orbitals to maximize multiplicity so that overall energy is minimum and therefore atom is stable (Hunds Rule of Maximum Multiplicity)

Thus carbon atom just have 2 unpaired electrons which are present in 2p orbitals.

Which element have electron configuration 1s2 2s2 2p2 ?

Carbon (C)

In what type of orbital is the outermost electron in Carbon atom?

Electron configuration of carbon is 1s2 2s2 2p2
From this it can be clearly observed that outermost electron in carbon atom is present in 2p orbital.

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