The bond formed when ammonia reacts with hydrogen ion to form ammonium ion is

Analyze the question: The question asks about the type of bond formed in the reaction NH₃ + H⁺ → NH₄⁺.

Concept: A dative (coordinate covalent) bond forms when one atom provides both electrons of the shared pair. The other atom contributes none. Ammonia has a lone pair on nitrogen. A hydrogen ion (H⁺) has no electrons, but it has an empty orbital that can accept a pair.

Step-by-step solution:

1. Nitrogen in NH₃ has 5 valence electrons. Three are used in bonds with hydrogen atoms, leaving one lone pair.
2. The H⁺ ion has no electrons (it is a hydrogen atom that has lost its only electron), so it has an empty 1s orbital.
3. Nitrogen donates its lone pair into the empty orbital of H⁺, forming a new N–H bond.
4. Because both electrons in this bond came from nitrogen alone, the bond is a dative (coordinate) covalent bond.

H⁺ + :NH₃ → [H–NH₃]⁺, which is NH₄⁺

Once formed, all four N–H bonds in NH₄⁺ are identical. But the question asks about the bond formed in this reaction, which is the dative bond.

Why not the others?

• A. Covalent: This is technically true in a general sense, since a dative bond is a type of covalent bond. But the question asks for the specific bond type, which is dative.
• C. Hydrogen bond: This is an intermolecular attraction, not the bond formed here.
• D. Ionic: There is no transfer of electrons between oppositely charged ions here. Electrons are shared.

Correct answer: B. Dative

Exam tip: Look for a lone pair + empty orbital. NH₃ → NH₄⁺, H₂O → H₃O⁺, and NH₃ → BF₃ adducts are all dative bonds. Whenever H⁺ is added to a molecule with a lone pair, think "dative."