Week 6, Halogen

Astatine, the heaviest of the known halogens, is only found in tiny amounts in nature due to its short half-life. The most stable of its isotopes lasts decays in 8.3 and turns into isotopes of lead. Astatine is black, becoming a purplish vapor when heated. Interestingly, Medeleev predicted the existence of astatine and called it eka-iodine but the element was not produced until 1940 and three years later it was found naturally.