astatine

as·ta·tine  (st-tn, -tn)

n. Symbol At

A highly unstable radioactive element, the heaviest of the halogen series, that resembles iodine in solution. Its longest lived isotope has a mass number of 210 and has a half-life of 8.3 hours. Atomic number 85; melting point 302°C; boiling point 337°C; valence probably 1, 3, 5, 7. See Table at element.

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[Greek astatos, unstable; see astasia + -ine.]

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astatine [ˈæstəˌtiːn -tɪn]

n

(Chemistry / Elements & Compounds) a radioactive element of the halogen series: a decay product of uranium and thorium that occurs naturally in minute amounts and is artificially produced by bombarding bismuth with alpha particles. Symbol: At; atomic no.: 85; half-life of most stable isotope, ²¹⁰At: 8.1 hours; probable valency: 1,3,5, or 7; melting pt.: 302°C; boiling pt.: 337°C (est.)

[from Greek astatos unstable (see astatic) + -ine²]

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astatine  (st-tn)

Symbol At

A highly unstable, rare, radioactive element that is the heaviest of the halogen elements. Its most stable isotope has a half-life of 8.3 hours. Atomic number 85; melting point 302°C; boiling point 337°C; valence probably 1, 3, 5, 7. See Periodic Table.

Thesaurus

Noun

1.

astatine - a highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium At, atomic number 85 chemical element, element - any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter halogen - any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions