actinoid
Học thuậtThân thiện
Definition
Adjective:
- Having a radial form; exhibiting radial symmetry: Describes an object, especially in biology, whose parts are arranged symmetrically around a central axis, like the spokes of a wheel.
Noun:
- Any of a series of radioactive elements with atomic numbers from 89 through 103: Refers to a specific group of chemical elements in the periodic table, also known as the actinide series.
Usage Examples
Adjective:
- The sea anemone is an actinoid creature, with its tentacles arranged in a circle.
- Biologists study actinoid symmetry in certain marine organisms.
Noun:
- Uranium and plutonium are well-known actinoids used in nuclear reactors.
- The actinoids are all radioactive and have similar chemical properties.
Advanced Usage
- In scientific literature, the noun form is often used interchangeably with "actinide." The term actinoid is sometimes preferred in formal IUPAC nomenclature.
- The chemistry of the actinoid elements is complex due to their radioactive nature.
Variants and Related Words
- Actinide (noun): A synonym for the noun form, more commonly used in chemistry.
- Radial (adjective): Similar in meaning to the adjective form, describing something arranged like rays coming from a center.
- Actinium (noun): The element (atomic number 89) from which the actinoid series gets its name.
Synonyms
- Adjective: radial, radially symmetrical, stellate.
- Noun: actinide.
Notes on Different Meanings
The two meanings are from distinct scientific fields (biology/geometry vs. chemistry). The adjectival meaning describes a shape or form, while the nominal meaning refers to a specific group of chemical elements. Context always clarifies which meaning is intended.
Adjective
- having a radial form
- starfish are actinoid--that is, they are radially symmetrical
Noun
- any of a series of radioactive elements with atomic numbers 89 through 103