astatine

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astatine (symbol At) Semimetallic radioactive element that is one of the halogens (group VII of the periodic table). It is rare in nature, and is found in radioactive decay. At211 will collect in the thyroid gland and is used in medicine as a radioactive tracer. Properties: at.no. 85; r.a.m. 211; m.p. 302°C (575.6°F); b.p. 377°C (710.6°F); most stable isotope At210 (half-life 8.3hr).

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