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.}


Discovery of the noble gases

{tag=Chemical substance}
{tag=Oxygen compound}
{wiki}

"Water" is the name for both:
* the <chemical compound> with <#chemical formula> H\sub[2]O
* the <liquid phase> of the <chemical substance> composed of the above <chemical compound>

\Image[https://upload.wikimedia.org/wikipedia/commons/8/8a/2006-02-13_Drop_before_impact.jpg]
{title=<Water> in a glass}

\Image[https://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Water-3D-balls-A.png/800px-Water-3D-balls-A.png]
{title=<Ball-and-stick model> of a <water molecule>}
{disambiguate=water}

\Image[https://upload.wikimedia.org/wikipedia/commons/3/33/Phase_diagram_of_water_simplified.svg]
{title=Simplified <phase diagram> of <water>}
{description=Note the <triple point> and <critical point (thermodynamics)> visible. <Phase diagrams> are so cool!}
{height=600}

\Image[https://upload.wikimedia.org/wikipedia/commons/0/08/Phase_diagram_of_water.svg]
{title=<Phase diagram> of <water>}
{description=Note all the obscure <phases of ice>.}
{height=600}


Ciro Santilli @cirosantilli 37

 Incoming links: Chemical compound