Carbon, hydrogen, nitrogen, oxygen--the famous elements atop the periodic table steal all the headlines. At the far end, in the table's highest numbers, lie unstable elements that only exist for fractions of a second before they radioactively decay. But in between lie the fields of forgotten nuclei: elements with funny names that nonetheless turn up in machines, medicines, and international intrigue.
Praseodymium, Atomic Number: 59
If you've ever welded metal, thank praseodymium that you can still see. Praseodymium is mixed with its periodic next-door neighbor, neodymium, to create didymium glass. The glass is transparent yellow but blocks infrared radiation, so didymium is used in safety goggles for glassblowing and welding masks.
All text by Andrew Moseman; Image: U.S. Navy