One of my posts will be chemical of the week – the good news is that I’m never going to run out of material for this one, we’ve 118 elements before we even start combining them ! I thought I’d start of with one of my favourites – that nasty little blighter fluorine ! No, it’s not found in your toothpaste (that’s fluoride) – what a difference one electron makes. Oh come on, you’ve got to love chemistry -it’s life or death ( ok unless you have toothpaste addiction). Fluorine stands proud at the top of Group 7 with a symbol that represents the shortened form of a bad word so what’s so bad about fluorine – well the fact is with seven valence electrons it really wants that final one electron badly and it’s going to do whatever it takes to get it (we meet it at A2 as a powerful oxidising agent – electrode potential of +2.87 V).
The good news for us is that you don’t find it languishing in the chemical store because it never hangs around having snagged an electron from anything in sight – that’s why it’s found in compounds not its elemental state. Back in 1813 Davy announced its existence but it wasn’t until 1886 that it was isolated with lots of injuries and deaths along the way. Henri Moissan received the 1906 Nobel Prize for this achievement.
So let’s get to the good stuff with this bad boy – fluorine is used in the production of uranium hexafluoride which is involved in reprocessing nuclear fuel (maybe not so bad I’m a nuclear fuel fan more of that later ) but also in the preparation of nuclear weapons. Natural uranium only contains 0.72% of the radioactive isotope U-235. When uranium metal reacts with fluorine, the gas uranium hexafluoride is produced which then means the radioactive U-235 content can be increased using gas centrifugation. So it looks like not only would exposure to fluorine gas on its own be enough to kill you (all it takes is to expose a poor rat to 400ppm for 25 mins) but it can be found doing a merry dance with radioactive uranium too !
If you want to find out more about fluorine here’s a link to molecule of the month (fantastic website)