The Periodic Table according to astronomers

And if you ask a cosmologist what the universe is made of, they go "Well, there's a lot of dark matter, and even more dark energy. And then there's a tiny bit of some matter or something idk lol."
- Read that as cosmetologist and was thoroughly confused.

*The Periodic Table according to Michael Jackson
- He₂
  
  Does that decay into SHeMoNa?
  Edit. Corrected my bad mixed up spelling

Plutonium is not a real element.
- Plutonium can be on the periodic table but we do not grant it the rank of element.
- It's a dwarf element.

Physicists are notorious for approximating, and astronomers are even worse. But there are some subfields where they care about being more precise, and you maybe break the periodic table into a handful of elements plus alphas. And there's that one or two people getting exquisite spectral resolution and signal-to-noise on a few stars and measuring the abundance of Technetium or whatever.
- It's why I fucking love astrophysics. There's so much handwaving because so much information is observed.
  But without the handwaving you can't find crazy ass things like nuclear fusion being behind the power of stars. You find these really big numbers everywhere that make the "normal stuff" negligible.
  It not that the precision isn't important, it's just not always relevant at particular scales, like the scale of space.

What about metallic hydrogen in the core of planets?
- "Wait, they're ALL metals?"
  "Always have been."
- Funnily enough, probably not a metal according to astronomers.

Iodine is a transition metal I will die on this hill.
- Care to defend your position? Iodine is certainly not in the d-block...
  
  The intended joke is that hypervalent iodine compounds like Dess-Martin periodinane flip between different oxidation states like you often see for transition metals. As an example, the mechanism usually drawn for oxidations by DMP is similar to those drawn for PCC/Jones reagent, where the electrons removed from the substrate are "banked" at the metal center. Obviously, redox chemistry is not at all limited to transition metals, but I am often surprised at iodine's propensity to engage in it. A lot of research over the past decade or two has also developed redox catalysis with these reagents, reactivity which is commonly (though again not always) the purview of transition metals.

That's because these two account for something like 99% of all normal matter in the universe