Question

What is the number of valence electrons in Nitrogen?

Answer 1

Hint: There is a difference between valence electrons and valency. Valence electrons are the total number of electrons present in the outermost shell of an atom. Valency is the total number of electrons gain, lose or share at the time of bond formation.

Complete answer:
The atomic number of nitrogen is 7. Or else we can find the atomic number of nitrogen through the periodic table. Nitrogen lies in the group 15.
As the Nitrogen atomic number is 7 therefore it has 7 protons and 7 electrons. Now we know the number of electrons we can find in the electronic configuration.
Electronic configuration is the arrangement of electrons on the orbitals. The nitrogen atom has a total of 7 electrons so, we have to put 7 electrons in orbitals. The electrons will be placed in different orbitals according to the energy level $:[1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p,7s,5f]$. Now, nitrogen electronic configuration $ = 1{s_2}2{s_2}2{p_3}$ .
After finding electronic configuration, we need to determine the valence shell.
The valence shell of an atom can be found from the highest number of principal quantum numbers which are expressed in the term of $n$, so that the valence shell of nitrogen is $2{s_2}2{p_3}$.
The total number of electrons present in the valence electrons present in the valence shell of an atom are called valence electrons, and there are a lot of five electrons present in the valence shell of nitrogen$(2{s_2}2{p_3})$. Thus nitrogen has five valence electrons.

Note:
 The valence electrons of nitrogen is 5 but it does not have d subshell so that the valency reduces to 3 from 5. For example, phosphorus pentachloride $(PC{l_5})$ can exist as phosphorus has d orbitals but nitrogen pentachloride $(NC{l_5})$ cannot exist. Although nitrogen has 5 electrons only a maximum of three can take part in bond formation, for example $[NC{l_3},N{H_3}]$.