Britannica Sources used in this answer

Why does lithium react with nitrogen while the other alkali metals generally do not?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. — alkali metal Modern version of the periodic table of the elements (printable).

Lithium is the only alkali metal that reacts directly with nitrogen to form a nitride ( $L i_{3} N$ ). This unique behavior occurs because lithium exhibits chemical properties more similar to the alkaline-earth metals, such as magnesium, than to the other members of its own group.12

This similarity is largely attributed to the fact that lithium possesses atomic and ionic radii comparable to those of magnesium. While the other alkali metals do not form stable nitrides, lithium's ability to react with nitrogen is consistent with its broader tendency to share characteristics with Group 2 elements, including the formation of stable hydrides and carbides that mirror those of elements like calcium.12