Question

If the elements $\mathrm{N},\mathrm{O}\mathrm{and}\mathrm{F}$ were to gain electrons to attain the nearest inert gas configuration, which ions do they convert to? What is the relationship between these ions?

Answer 1

Attaining inert gas configuration:

• The nearest inert gas configuration for $\mathrm{N},\mathrm{O}\mathrm{and}\mathrm{F}$ is 2, 8 which is the electronic configuration of Neon
• To attain inert gas configuration, we need to know the electronic configuration of $\mathrm{N},\mathrm{O}\mathrm{and}\mathrm{F}$

Electron configuration: [Atomic number for $\mathrm{N}=7,\mathrm{O}=8,\mathrm{and}\mathrm{F}=9$]

Electronic configuration of $\mathrm{N}=2,5$

Electronic configuration of $\mathrm{O}=2,6$

Electronic configuration of $\mathrm{F}=2,7$

Electron needs to attain noble gas configuration:

• To attain the nearest inert gas configuration, nitrogen needs 3 electrons to be added, $\mathrm{O}$ needs 2 electrons, and $\mathrm{F}$ needs 1 electron. This no. of electrons to complete its octet configuration is called the valency of the atom.

Formation of ions:

• Hence they converted to ions, when they gain electrons they become anions, and when they give up electrons they become cations.
• In the case of nitrogen, it can neither accept nor gain three electrons. One way to complete its octet is by sharing electrons. So, nitrogen forms a covalent bond to complete its octet. it shares 3 electrons with another atom through a covalent bond.$\left({\mathrm{N}}^{3-}\right)$
• In the case of oxygen, it accepts 2 electrons and becomes an anion$\left({\mathrm{O}}^{2-}\right)$
• In the case of fluorine, it accepts 1 electron and becomes an anion$\left({\mathrm{F}}^{1-}\right)$.

Periodic trends:

• The relationship between these ions are increasing trend of electronegativity, As we move along a period from left to right, the electronegativity increases, that is their tendency to accept electrons increases, hence fluorine is the most electronegative one among them.

Hence the decreasing order of electronegativity is $\mathrm{F}>\mathrm{O}>\mathrm{N}$