Definition

Noun: 1. The chemical element Helium: "Atomic number 2" is the scientific designation for the chemical element helium (He). It refers to the element's defining property: having two protons in its atomic nucleus. It is a very light, colorless, odorless, and inert (non-reactive) noble gas.

Usage Examples

• Noun:
  • The balloon was filled with atomic number 2, causing it to float.
  • Atomic number 2 is the second most abundant element in the observable universe.
  • Scientists study the properties of atomic number 2 at extremely low temperatures.

Advanced Usage

• Scientific and Technical Context: The term "atomic number 2" is used almost exclusively in formal scientific, educational, or technical writing to precisely identify the element. In most other contexts, the common name "helium" is used.
  • The periodic table lists elements in order of increasing atomic number; therefore, atomic number 2 comes directly after hydrogen.

Variants and Related Words

• Helium (n): The common name for atomic number 2.
  • Helium is used to cool superconducting magnets in MRI machines.
• He (symbol): The standard chemical symbol for helium/atomic number 2.
  • The formula indicated the presence of He gas.

Synonyms

• Helium: The direct and most common synonym.
• Noble gas / Inert gas: A categorical synonym describing its chemical family and property.

Related Phrases/Idioms

(This term is a precise scientific identifier and is not used in idiomatic expressions or phrasal verbs.)

Noun

1. a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and Kansas)