As has already been noted, the word gas was invented by the Dutch chemist J. B. Van Helmont, based on Greek χάος "chaos".
Van Helmont also invented the obsolete word blas, a "term for a supposed ‘flatus’ or influence of the stars, producing changes of weather," altho this was presumably based on Middle English blas "blast, breath", or Dutch blas "bladder".
χάος is from Proto-Indo-European *ǵʰēu- "yawn, gape". In English, *ǵʰēu- became gōma then gums, which are exposed when you yawn.
Gum that you chew is based on gum "the secretion from certain trees," from Latin gummi, cummi from Greek κόμμι.
PS: because it's that time of year: grime and Christ.