Question

Write the electronic configuration of the Boron.

Answer 1

Hint: Boron belongs to the group no. 13 and it’s atomic no. is 5. So, it has 5 electrons. General valence electronic configuration of group 13 elements is $n{s}^{2}n{p}^1$. To write the electronic configuration of boron, fill its 5 electrons in the orbitals arranged in order of increasing energies, according to Aufbau Principle.

Complete step by step solution:
An electron in an atom is characterised by 4 quantum numbers, and the principal quantum number $(n)$ defines the main energy level known as the shell. Each shell consists of one or more subshells or sub-levels. Each subshell is assigned by azimuthal quantum no. ($l$) and $l$have values from 0 to $n-1$ Also, each subshell has orbitals equal to $$2l+1$$ . The distribution of electrons into orbitals of an atom is called its electronic configuration.
Boron has atomic no. 5 and it is represented by symbol the B. It belongs to group 13 of p-block. Group 13 elements outermost or valence electronic configuration is $$\left[E\right]n{s}^{2}n{p}^1$$, where E is an inert gas configuration).
To find the electronic configuration of boron, fill 5 electrons of boron in orbitals according to Aufbau principle. Consequently, electronic configuration of boron will be :$$1s^{2}2s^{2}2p^1$$.
Now, to write the noble gas electronic configuration of boron, we need to find the noble gas that comes before boron in the periodic table and it is helium ( electronic configuration of helium is $$1s^2$$).
Therefore, the noble gas electronic configuration of boron is $$\left[He\right]2s^{2}2p^1$$. The 2 in $2s^{2}and2p^2$ denotes the shell no (n) and shell number denotes the period no. to which the element belongs. Thus, boron belongs to period 2 of the periodic table.

Note: The orbital picture of boron can be represented as :
$s$- orbital can hold up maximum 2 electrons, $p$-orbitals can hold maximum 6 electrons.