Page 24 - Curriculum Visions Dynamic Book

Astatine (At)
Element 85. It is a radioactive halogen element and is the heaviest member in group 7 in the Periodic Table.The longest half-life of astatine is 8.3 hours.As a result,
it decays extremely quickly. It is made in nuclear reactors.
Discovery
It was discovered during experiments
in a nuclear reactor by Dale R. Corson, K. R. MacKenzie and Emilio Segrè at the University of California in 1940 by bombarding bismuth with alpha particles.
Technology
It has no uses.
Geology
It does not occur naturally except as part of the decay of uranium and thorium minerals.
Biology
As a radioactive halogen it is theoretically harmful but is produced in tiny quantities.
The mineral barite is made of barium sulphate.
Key facts...
Name: astatine
Symbol: At
Atomic number: 85
Atomic weight: 210
Position in Periodic Table: group 7 (17) (halogens);
period 6
State at room temperature: solid
Colour: metallic
Density: n/a
Melting point: 337°C
Boiling point: n/a
Origin of name: from the Greek word astatos,
meaning unstable because of its short half-life. Shell pattern of electrons: 2–8–18–32–18–7
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