Definition

1. Adjective:
   • Containing or characteristic of phosphorus: Describes something that contains the chemical element phosphorus (P) or has properties associated with it.
   • Relating to or derived from phosphorus: Pertaining to compounds in which phosphorus is present, especially in a lower valence state compared to phosphoric compounds.

Usage Examples

• Adjective:
  • The match head has a phosphorous coating that ignites when struck.
  • Scientists studied the phosphorous compounds found in the soil sample.
  • A phosphorous glow was visible in the dark cave.

Advanced Usage

• "Phosphorous acid": A specific chemical compound (H₃PO₃), distinct from phosphoric acid (H₃PO₄). It is an example of a phosphorus compound in a +3 oxidation state.
  • Phosphorous acid is often used as a reducing agent.

Variants and Related Words

• Phosphorus (n): The chemical element (symbol P) itself.
  • Red phosphorus is a less reactive allotrope.
• Phosphoric (adj): Containing phosphorus in a higher oxidation state, especially +5, as in phosphoric acid (H₃PO₄).
  • Phosphoric acid is commonly used in soft drinks.
• Phosphate (n): A salt or ester of phosphoric acid.
  • Calcium phosphate is important for bone health.

Synonyms

• Phosphoric (when referring to the pentavalent state, but note the technical distinction in valence).

Notes on Meaning and Usage

• Technical Distinction: In precise chemical terminology, phosphorous (with an 'o' and ending in '-ous') typically refers to compounds where phosphorus has a valence of +3. In contrast, phosphoric (ending in '-ic') refers to the +5 valence state. This is analogous to the distinction between (H₂SO₃) and (H₂SO₄) acids.
• Common Confusion: The word phosphorous is often confused with the element name phosphorus. Remember: Phosphorus is the noun (the element), while phosphorous is the adjective (describing something containing that element, typically in the +3 state).

Adjective

1. containing or characteristic of phosphorus
   • phosphoric acid