Definition

1. Noun:
   • A chemical element: A soft, silvery, metallic element belonging to the lanthanide series (rare earth group). It is characterized by having no stable isotopes and is typically obtained as a product of nuclear fission.

Usage

• Noun: This term is used almost exclusively in scientific and technical contexts, specifically in chemistry, physics, and nuclear engineering, to refer to the element with the number 61 in the periodic table.
  • The sample was found to contain traces of atomic number 61.
  • Atomic number 61 is studied for its radioactive properties.

Advanced Usage

• In nuclear chemistry: The term is used to discuss the element's role as a fission product.
  • The reactor's waste products include several isotopes of atomic number 61.

Variants and Related Words

• Promethium (Pm): This is the element's name and the standard, more common term for "atomic number 61".
  • Promethium, atomic number 61, is used in some types of batteries.
• Lanthanide: The series of elements to which atomic number 61 belongs.
• Rare earth element: The broader category that includes this element.

Synonyms

• Promethium: The name of the element.
• Pm: The chemical symbol for the element.

Notes on Meaning

• The phrase "atomic number 61" is a definitive identifier based on the element's number of protons. Its primary meaning is the element promethium itself. It has no other common meanings outside of this scientific identification.

Noun

1. a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium