Definition

1. Noun:
   • A chemical element: "atomic number 77" is the scientific term for the metallic element with 77 protons in its atomic nucleus. It is a member of the platinum group of metals.
   • A specific metal: It refers to a heavy, brittle, silvery-white transition metal known for its high density, corrosion resistance, and occurrence alongside other platinum-group metals.

Usage

• Scientific and Technical Context: The term "atomic number 77" is used primarily in chemistry, physics, and materials science to specify the element unambiguously by its fundamental property (proton count).
  • The isotope in question has the mass number 192, but it remains atomic number 77.
  • All atoms of atomic number 77 must have exactly 77 protons.

Advanced Usage

• The term "atomic number 77" is the definitive identifier for the element, which is more commonly known by its element name and symbol in most contexts.

Variants and Related Words

• Iridium: This is the common name for the element with atomic number 77. Its chemical symbol is Ir.
  • The tip of high-quality fountain pens is often made of iridium.
• Platinum-group metal: A category of six precious metals that includes atomic number 77 (iridium), along with ruthenium, rhodium, palladium, osmium, and platinum.

Synonyms

• Iridium (the element name)
• Ir (the chemical symbol)

Notes

• Unlike many dictionary entries, "atomic number 77" does not have associated idioms, phrasal verbs, or multiple common meanings. Its meaning is precise and technical, referring exclusively to the chemical element iridium.

Noun

1. a heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium