are the far right elements on the periodic table. On the earth they are scarce so we don’t see much of them, because they do not react well with anything. In fact until around the 50’s they hadn’t found anything that they would react with any of the gases. But then someone found out that Fluorine one of the most reactive elements could form compounds with Xenon. Later they found that it could react with most of the other gases. Helium is one of the more scarce noble gases on earth but in the universe it makes up 25% of it. Heliu ....