Nitrogen belongs to the second period and has the valence shell electronic configuration $2s^2 2p^3$. It has no vacant $d$-orbitals in its valence shell ($n=2$ has only $s$ and $p$ subshells), so it cannot expand its octet to form pentahalides like $\text{NCl}_5$. In contrast, phosphorus belongs to the third period ($3s^2 3p^3$) and possesses vacant $3d$-orbitals, allowing it to expand its covalency to 5 and form $\text{PCl}_5$.

In Haber's industrial process for ammonia manufacture, the sequence of operations is:

• Compression (C): The pure $\text{N}_2$ and $\text{H}_2$ mixture (1:3 ratio) is compressed to about $200\text{ atm}$.
• Catalytic Reaction (B): The compressed gases pass over the catalyst (iron oxide with $\text{K}_2\text{O}$ and $\text{Al}_2\text{O}_3$) at around $700\text{ K}$.
• Condensation (A): The reacted gases leave the converter and ammonia is condensed into liquid form.
• Recirculation (D): Unreacted $\text{N}_2$ and $\text{H}_2$ gases are recycled back via a circulating pump.

Laughing gas is dinitrogen monoxide (nitrous oxide), having the chemical formula $\text{N}_2\text{O}$. It is a colourless, non-flammable gas with a slightly sweet scent and taste, widely used as an anesthetic and analgesic.

Chlorine reacts with hot and concentrated sodium hydroxide solution via a disproportionation reaction to form sodium chloride and sodium chlorate ($\text{NaClO}_3$):

In $\text{NaClO}_3$: