Back to Elements
    At

    Astatine

    Halogen

    Atomic Number: 85 • Atomic Mass: 210.0000 u • Period: 6 • Group: 17

    Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁵
    Phase: Solid
    Electronegativity: 2.2
    Polonium (Po)Radon (Rn)
    OverviewPropertiesAtomic StructureOccurrenceApplicationsHistory

    Overview

    Astatine is the chemical element with the symbol At and atomic number 85. It belongs to the Halogen group and is located in period 6 of the periodic table. It exists as a solid under standard conditions.

    Basic Information

    • Symbol:At
    • Atomic Number:85
    • Atomic Mass:210.0000 u
    • Group:17
    • Period:6
    • Category:Halogen
    • Phase at STP:Solid
    • Electronegativity:2.2 (Pauling scale)

    Key Facts

    Fun Fact #1

    Rarest naturally occurring element on Earth's crust

    Fun Fact #2

    All isotopes are radioactive

    Common Uses

    • Cancer treatment (experimental)
    • Research
    • Nuclear medicine