Definition

1. Noun:
   • A positively charged polyatomic ion: The ammonium ion is a chemical species with the formula NH₄⁺. It is formed when ammonia (NH₃) gains a proton (H⁺). In chemical behavior, it often resembles ions of alkali metals, such as sodium (Na⁺) or potassium (K⁺).

Usage Examples

• Noun:
  • In aqueous solution, the ammonium ion is in equilibrium with ammonia.
  • Many fertilizers contain salts of the ammonium ion, like ammonium nitrate.
  • The ammonium ion is a common byproduct in the metabolic breakdown of proteins and nucleic acids.

Advanced Usage

• "Ammonium ion concentration": Refers to the amount of NH₄⁺ present in a solution, often measured to assess water quality or soil chemistry.
  • High ammonium ion concentration in the lake indicates potential pollution from agricultural runoff.
• "Ammonium ion exchange": Describes a process where ammonium ions are swapped for other ions, commonly used in water softening or purification.
  • The resin performs ammonium ion exchange to remove contaminants from the wastewater.

Variants and Related Words

• Ammonium (n): A general term for the univalent cation NH₄⁺ or for compounds containing it.
  • Ammonium chloride is a white crystalline salt.
• Ammonia (n): The precursor molecule (NH₃) from which the ammonium ion is derived.
  • Ammonia has a sharp, pungent odor.

Synonyms

• NH₄⁺: The chemical formula used as a direct synonym in scientific contexts.
• Ammonium cation: A more formal term emphasizing its positive charge.

Related Phrases / Terms

• "Like an alkali metal ion": A key descriptive phrase noting its chemical similarity to Group 1 elements.
  • The ammonium ion behaves like an alkali metal ion in its tendency to form soluble salts.

Noun

1. the ion NH4 derived from ammonia; behaves in many respects like an alkali metal ion