Definition

1. Noun:
   • A chemical element: "atomic number 90" is the scientific designation for the chemical element thorium. It is a soft, silvery-white, tetravalent, radioactive metal. Its isotope with mass number 232 is used as a fuel source in nuclear reactors. It is found naturally in minerals such as thorite and monazite sands.

Usage Examples

• Noun:
  • The periodic table lists the element with atomic number 90 as thorium.
  • Scientists studied the properties of atomic number 90 for potential use in advanced nuclear power systems.

Advanced Usage

• In scientific nomenclature: The term "atomic number 90" is used primarily in formal scientific, technical, and educational contexts to precisely identify the element by its number of protons, especially when discussing periodic trends or nuclear properties.
  • The research paper compared the nuclear stability of atomic number 90 with that of neighboring actinides.

Variants and Related Words

• Thorium (Th): The common name for the element with atomic number 90.
  • Thorium-232 is the most stable isotope of atomic number 90.
• Actinide: The series of elements in the periodic table to which atomic number 90 belongs.
  • Atomic number 90 is a member of the actinide series.

Synonyms

• Thorium: The direct and most common synonym.
• Element 90: An alternative numerical designation.
• Th: The chemical symbol for atomic number 90.

Related Phrases

• Atomic number: The fundamental property that defines an element (the number of protons in its nucleus). "Atomic number 90" is a specific instance of this concept.
  • Understanding atomic number is key to reading the periodic table; for example, atomic number 90 corresponds to thorium.

Noun

1. a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands