Introduction:
Nitrogen gas (N2) is a diatomic molecule composed of two nitrogen atoms held together by a strong triple bond. Alkali metals are a group of elements found in the first column of the periodic table, including lithium (Li), sodium (Na), potassium (K), etc. These metals are highly reactive due to their low ionization energy and readily lose their outermost electron to form cations.

Why N2 does not react with alkali metals:
There are several reasons why N2 does not react with alkali metals.

1. Stability of the Nitrogen Molecule:
The nitrogen molecule (N2) possesses a strong triple bond due to the overlap of orbitals between the two nitrogen atoms. This bond is very stable and requires a significant amount of energy to break. The alkali metals, on the other hand, have a relatively low ionization energy, making it easier for them to lose electrons and form cations. The energy required to break the triple bond in N2 is much greater than the energy released by the formation of alkali metal cations, making the reaction unfavorable.

2. Lack of Available Orbital for Bonding:
Alkali metals have a single valence electron in their outermost shell, which is responsible for their high reactivity. However, this electron is in an s orbital, and the nitrogen molecule requires an empty p orbital for bonding. Since alkali metals do not have any available p orbitals in their valence shells, they cannot form stable bonds with nitrogen.

3. Electronegativity Difference:
Nitrogen is an electronegative element, meaning it has a strong affinity for electrons. Alkali metals, on the other hand, have a low electronegativity and tend to lose electrons rather than gain them. The large electronegativity difference between nitrogen and alkali metals makes it difficult for them to form stable bonds.

4. Formation of Nitrides:
While N2 does not react directly with alkali metals, it can react with alkali metal nitrides. In these reactions, nitrogen reacts with the metal to form a nitride compound, such as lithium nitride (Li3N) or sodium nitride (Na3N). However, these reactions require high temperatures and pressures, and the resulting nitrides are highly stable compounds.

Conclusion:
In summary, the lack of available orbitals for bonding, the stability of the nitrogen molecule's triple bond, the electronegativity difference between nitrogen and alkali metals, and the formation of stable nitrides all contribute to the lack of reactivity between N2 and alkali metals. While N2 does not react directly with alkali metals under normal conditions, it can form nitride compounds under extreme conditions.

They do not occur naturally because they react readily with air and moisture and so need to be stored under oil. One of the signature reactions of alkalimetals is their reaction with water to form alkaline solutions, for example sodium reacts with water to formsodium hydroxide – caustic soda.