Question

How is \[NH_4^ + \]formed?

Answer 1

Hint: The formation of ammonium ions involves the protonation of ammonia by transferring hydrogen ions to its lone pair of electrons. The octet should be complete when the Hydrogen ion and Ammonia ion are formed.

Complete Step by Step Solution:
1. The reaction of ammonia molecule \[\left( {N{H_3}} \right)\]and a proton \[\left( {{H^ + }} \right)\]cation then the unshared or the lone pair of electrons in the Nitrogen atom form a coordinate or dative bonding with the cation and produce an Ammonium ion \[NH_4^ + \].
\[N{H_3}(g) + {H^ + }(g) \to NH_4^ + (g)\]
2. The Ammonia molecule in the above reaction uses three valence electrons of Nitrogen in the outer energy level for structure and the bonding leaves two unpaired electrons which are called lone pairs.
3. The Hydrogen ion in the above reaction has no electron and it has a proton. This Hydrogen reacts with the lone pairs to form a dative or coordinate bond.
4. The Ammonia ion has a complete octet structure in the Nitrogen atom and is also electron-rich; then the charge density causes a Hydrogen ion which is a proton.
5. The positive charge on the Ammonium ion is due to the formal positive charge on the Nitrogen atom.

Additional information:
1. Dative bonding: It is a type of covalent bond in which both the electrons for sharing are contributed by only one of the atoms that form the bond.
2. In this type of bonding, an atom donates its lone pair of electrons as a nucleophile to another species which lacks electrons, an electrophile to stabilise it.

Note: A dative bond is not as strong as a true covalent bond in which two atoms share electrons for mutual stability.