= Discovery of the noble gases
Discovering them was not so easy because they don't form <chemical compounds>. So they exist only as gases. And <Helium> disperses off into space.
<Argon> was the first to be found by density considerations because it is so abundant on <Earth's atmosphere> (~1%): <Argon is abundant on Earth's atmosphere because it comes from the decay of Potassium-40>.
Then basically all of the others were discovered by <spectral lines>. <Helium> notably was first found on the <Sun> like that, and only later on Earth! Thus its name. Pretty cool.
\Video[https://www.youtube.com/watch?v=loqudG71uBM]
{title=The Incredible Discovery of the LEAST Reactive Elements by Chemistorian}
{description=2024. Great video.}