weeks 6 and 7: Halogen of the week

My Halogen of the Week is Astatine. I picked it because I had never heard of it. It's number is 85, it's abbreviation is At. It's weight is 210, in parentheses, and I don't know what that's about. It's solid at 298 degrees Kelvin, metallic in color and classified as semi-metallic. But before you start feeling friendly about it, I should tell you that it's radioactive, essentially unavailable in nature and made only in nuclear reactors. It's longest lived isotope has a half-life of only 8.3 hours. It has about 20 isotopes and they are all radioactive. And possibly it accumulates in the thyroid like iodine. Sounds fairly horrifying, and it just goes to show you that you can't just walk up and make friends with an element just because it's in the periodic table. Best to google it first before you give out your phone number. The odd thing is that the website I went to had a picture of a rock with Astatine in it -- I have no idea how that happened.