At

Electrons: 2-8-18-32-18-7
Oxidation States: ±1, 3, 5, 7
Atomic Weight: [210]
Phase: Solid
M.P.: 575 K
(302 °C, 576 °F)
B.P.: ? 610 K
(? 337 °C, ? 639 °F)

Occurrence:
This highly radioactive element has been confirmed by mass spectrometers to behave chemically much like other halogens, especially iodine. With the possible exception of francium, astatine is the rarest naturally occurring element with the total amount in Earth's crust estimated to be less than 1 oz (28 g) at any one time; this amounts to less than one teaspoon of the element. The Guinness Book of Records has dubbed the element the rarest on Earth, stating: "Only around 0.9 oz (25 g) of the element astatine (At) occurs naturally in the Earth's crust."