Boron nitride is isoelectronic with

Total number of electrons in Boron nitride (BN) is:

$\begin{array}{ccc}\mathrm{Tiotal} \mathrm{number} \mathrm{of} \mathrm{electrons}& =& \mathrm{Number} \mathrm{of} \mathrm{electrons} \mathrm{of} \mathrm{B}+\mathrm{Number} \mathrm{of} \mathrm{electrons} \mathrm{of} \mathrm{N}\\ & =& 5+7\\ & =& 12\end{array}$

Total number of electrons in C₂ is:

$\begin{array}{ccc}\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{electrons}& =& 2(\mathrm{Number} \mathrm{of} \mathrm{electrons} \mathrm{of} \mathrm{C})\\ & =& 2\left(6\right)\\ & =& 12\end{array}$

Total number of electrons in B₂ is:

$\begin{array}{ccc}\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{electrons}& =& 2(\mathrm{Number} \mathrm{ofelectrons} \mathrm{of} \mathrm{B})\\ & =& 2\left(5\right)\\ & =& 10\end{array}$

Total number of electrons in N₂ is:

$\begin{array}{ccc}\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{electrons}& =& 2(\mathrm{Number} \mathrm{of} \mathrm{electrons} \mathrm{of} \mathrm{N})\\ & =& 2\left(7\right)\\ & =& 14\end{array}$

Total number of electrons of O₂ is:

$\begin{array}{ccc}\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{electrons}& =& 2(\mathrm{Number} \mathrm{of} \mathrm{electrons} \mathrm{of} \mathrm{O})\\ & =& 2\left(8\right)\\ & =& 16\end{array}$
Hence, BN and C₂ are isoelectronic.