Element of the week: thorium | video | @GrrlScientist

What does toothpaste, the Norse god of thunder and the word "pyrophoric" share in common?This week, we meet thorium, a chemical element with the symbol Th and atomic number 90. This element is a bit unusual since it is the first element we've met that was named for a character in Norse mythology: it was named in honour of the Norse god of thunder (and war), Thor. Swedish chemist Jöns Jakob Berzelius initially thought he had discovered this element in 1815 but soon realised that he had misidentified yttrium phosphate as being a new element, thorium. Berzelius apparently liked the name "thorium", since he reused it in 1829 when he was given a newly discovered mineral by Norwegian mineralogist Morten Thrane Esmark. It was from this rock that Berzelius extracted and identified thorium. Even though we are working our way through the actinoid/actinide series, which is filled with what I think of as "invisible" elements, thorium is nice because it actually has a physical -- therefore photographable -- presence that I can share with you (refer to the above photograph). Besides being photographable, there is something else to love about thorium: it gives us the chance to learn a useful new adjective, pyrophoric, which comes from the Greek for "fire-bearing". Pure thorium has the delightful quality of spontaneously igniting into flames when exposed to air. Thorium is the most common actinoid and is surprisingly common in the wild, occurring in small amounts in most rocks and soils in ...
Source: Guardian Unlimited Science - Category: Science Authors: Tags: Blogposts guardian.co.uk Science Source Type: news