Question

Explain the following:
i) NO2 is a better electrophile as compared to NH4.

Answer 1

"Electrophiles are positively charged or neutral species having vacant orbitals that are attracted to an electron rich centre. It participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile"

In ammonium ion, nitrogen is bonded to four hydrogen atoms and shares electrons with them. Nitrogen atom has full octet. All the orbitals are fully filled. Hence, nitrogen does not have space for any additional electrons.

In nitronium ion nitrogen atom does not have full octet around it (one double bond with oxygen and one co-ordinate bond with the other atom of oxygen), hence it always seeks for an electron to join.