Question

How do you write the noble-gas electron configuration for carbon?

Answer 1

Hint The atomic number of carbon is 6. Trace the noble gas present in the previous period with respect to carbon.

Complete step by step solution:
In the question it is asked how will be the noble gas configuration of a carbon atom. From the lower classes we are very familiar with the elements and its atomic number and positioning in the periodic table. We know that the elements are placed in periodic take in accordance with the increasing order of the periodic table. And the atomic number of the element gives the number of electrons and protons in the atom whereas the atomic mass number is the sum total of the number of protons and neutrons in the atom.
Now in the question we are supposed to write the noble gas electronic configuration. To solve this problem we should know the difference between the electronic configuration and noble gas electronic configuration of an atom.
The electronic configuration is the representation of the total number of electrons in each orbitals of the atom in the increasing order of their energy.
But in noble gas electronic configuration, we will insert the chemical notation of the noble gas which is present in the previous period and write the further electrons present other than those present in the orbitals of the noble gas.
It is quite confusing to explain with the aid of words. Let’s solve the problem and get an idea and difference between the two types of representation of electrons in carbon.
-We know that the atomic number of carbon is 6.Therefore there will be 6 electrons present in its o-orbitals.
-The carbon atom belongs to the second period of the periodic table.
Now let’s write the electronic configuration of carbon as,
$\text{Electronic configuration of C=1}{{\text{s}}^{2}}2{{s}^{2}}2{{p}^{2}}$
Now we have to know the noble gas present in the first period. Noble gas are those elements which have completely filled configurations. In the first shell there will be only one shell which is the K shell and it can accommodate only two electrons. Hence the element with atomic number 2 will be the noble gas I first period.
The element with atomic number 2 is He which is a noble gas.
C atom has four more electrons and a new shell than the He atom.
Hence we can write the noble-gas electronic configuration of C as,
$\text{Noble gas electronic configuration of C=}\left[ He \right]2{{s}^{2}}2{{p}^{2}}$

Note: We should know the atomic number of the elements, so that we could write the electronic configuration of the atom and we should be thorough with the order of orbitals and number of electrons each shell can accommodate to write the configuration of atoms.
The elements placed in group 18 are called the noble gas electrons which have completely filled configurations and are highly stable and unreactive.