atomic number 2

Noun atomic number 2 has 1 sense

• atomic number 2(n = noun.substance) he, helium - 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);
is a kind of chemical element, element, argonon, inert gas, noble gas