Question

Which of the following elements do not react directly with nitrogen to form nitride?

• A. $Na$
• B. $Li$
• C. $K$
• D. $Rb$

Answer 1

Answer: (A), (C), (D)

$Rb$

The alkali metal that reacts with nitrogen to form nitride is lithium.
$6Li+N_2\stackrel{\Delta }{⟶}2L{i}_{3}N\left(s\right)$
This is because the lattice energy released when $Li$ forms lithium nitride is high enough to compensate for high ionisation energy and electron gain enthalpy involved in the process.