Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun atomic_number_2

1 sense of atomic number 2

Sense 1
helium, He, atomic number 2 -- (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))
       => chemical element, element -- (any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter)
       => noble gas, inert gas, argonon -- (any of the chemically inert gaseous elements of the helium group in the periodic table)