Definition

1. Noun:
   • A chemical element: "atomic number 72" is the systematic name for the metallic element hafnium (Hf). It is a grey, tetravalent (having a valence of four) transition metal.
   • A specific property: The term explicitly refers to the element's defining property: the number of protons in its atomic nucleus, which is 72.

Usage Examples

• Noun:
  • Hafnium, atomic number 72, is used in control rods for nuclear reactors.
  • The chemist identified the sample as the element with atomic number 72.

Advanced Usage

• Scientific and technical contexts: The term "atomic number 72" is primarily used in systematic scientific nomenclature, periodic table discussions, and technical literature to specify the element unambiguously by its fundamental property rather than its common name.
  • Isotopes of atomic number 72 are studied for their nuclear properties.

Variants and Related Words

• Hafnium (Hf): The common name for the element with atomic number 72.
• Element 72: A synonymous systematic designation.

Synonyms

• Hafnium: The standard name for the element.
• Hf: The chemical symbol.

Notes on Meaning

The term "atomic number 72" has a single, precise meaning in chemistry and physics, referring exclusively to the element hafnium. It is not used in everyday language but is crucial for precise scientific communication.

Noun

1. a grey tetravalent metallic element that resembles zirconium chemically and is found in zirconium minerals; used in filaments for its ready emission of electrons