a rare element of the halogen family. Symbol: At; atomic number: 85.
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)
radioactive element, named 1947, from Greek astatos “unstable” (see astatic) + chemical suffix -ine (2). So called for its short half-life and lack of stable isotopes. “The element appears not to have a stable form and probably does not exist in nature” [Flood, “Origin of Chemical Names”].
astatine as·ta·tine (ās’tə-tēn’, -tĭn)
A radioactive halogen element. Its longest lived isotope has a mass number of 210 and a half-life of 8.1 hours. Atomic number 85; melting point 302°C; boiling point 337°C; valence probably 1, 3, 5, 7.
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.
noun John. 1688–1743, English potter; earliest of the great Staffordshire potters Historical Examples astbury of Shelton, early in the 18th century, made red crouch, and white stoneware. The Collector’s Handbook to Keramics of the Renaissance and Modern Periods William Chaffers astbury saw the dust, and it at once occurred to him that it might be […]
astc Association of Science and Technology Centers
aste Association of State and Territorial Epidemiologists Historical Examples If she don’t make ‘aste, I shan’t ‘ave time to get ‘alf a pint afore I go ‘ome! Punch, or the London Charivari, Vol. 104, May 20, 1893 Various I don’t vish to ‘urry you—but I vant you to mike ‘aste—&c., &c. Voces Populi F. Anstey […]
asteatosis asteatosis a·ste·a·to·sis (ə-stē’ə-tō’sĭs, ās’tē-) n. Diminished or arrested action of the sebaceous glands.
n. “genteel irony, polite mockery,” 1580s, from Greek asteismos “wit, witticism,” from asteios “of a city or town” (as opposed to “country”), from asty “town, city,” especially (without the article) “Athens.”