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Understanding the element
Astatine (At) is chemical element 85. It belongs to the halogens, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.
Where do we encounter it?
In practice, it turns up most often in scientific research, nuclear medicine and chemical synthesis.
scientific researchnuclear medicinechemical synthesis
Standard atomic weightNo standard atomic weight
What its position in the table tells us
Astatine sits in period 6, group 17 and the P block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.
Worth remembering
Astatine is radioactive, so its chemistry cannot be separated from nuclear physics and radiation safety
Astatine is radioactive, so its chemistry cannot be separated from nuclear physics and radiation safety