When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called

Analyze the question: NH₃ + H⁺ → NH₄⁺. We need to name the type of bond that forms between the ammonia molecule and the hydrogen ion.

Explain the concept:

• In NH₃, nitrogen has a lone pair of electrons (it uses 3 of its 5 valence electrons to bond with 3 hydrogens).
• The H⁺ ion has no electrons (an empty 1s orbital).
• Nitrogen donates its lone pair to H⁺, and the two atoms share that pair of electrons.
• A bond formed by sharing electrons is a covalent bond. Because both shared electrons come from one atom (nitrogen), it is a special type called a dative (coordinate) covalent bond.

Step-by-step solution:

1. NH₃ has the structure H–N–H with H below, and a lone pair on N.
2. H⁺ approaches the lone pair.
3. N donates the lone pair → N–H bond forms.
4. Once formed, all four N–H bonds in NH₄⁺ are identical. You cannot tell which one was the dative bond.

Checking the options:

• A. Electrovalent bond: this means ionic (transfer of electrons). It is not correct, because no electron is transferred.
• B. Compound bond: not a recognized type of chemical bond.
• C. Ionic bond: the same as electrovalent, so it is incorrect.
• D. Covalent bond: correct. It is the dative or coordinate covalent bond, a type of covalent bond.

The NH₄⁺ ion as a whole carries a charge and forms ionic compounds (such as NH₄Cl) with other ions, but the bond within the ion, between N and H, is covalent.

Answer: D, covalent bond (specifically a dative/coordinate covalent bond).

Exam tip: Whenever you see NH₄⁺, H₃O⁺, or the formation of complexes, think "lone pair donated to an empty orbital", which is a coordinate (dative) covalent bond. Remember: dative = both electrons from one atom, but still covalent.