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    As

    Arsenic

    Metalloid

    Atomic Number: 33 • Atomic Mass: 74.9220 u • Period: 4 • Group: 15

    Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p³
    Phase: Solid
    Electronegativity: 2.18
    Germanium (Ge)Selenium (Se)
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    Physical & Chemical Properties

    Physical Properties

    • •Steel-gray, brittle metalloid with three allotropic forms
    • •Most stable form is metallic gray arsenic
    • •Yellow allotrope is most reactive form
    • •Sublimes when heated rather than melting under normal pressure
    • •Good conductor of heat but poor conductor of electricity
    Melting Point

    1090 K (816.85 °C, 1502.33 °F)

    Boiling Point

    887 K (613.85 °C, 1136.93 °F)

    Density

    5.776 g/cm³

    Electronegativity

    2.18 (Pauling scale)

    Chemical Properties

    • •Main oxidation states are -3, +3, and +5
    • •Forms covalent bonds with many elements
    • •Oxidizes in air, forming arsenic trioxide
    • •Combines readily with metals to form arsenides
    • •Many compounds are highly toxic

    Electron Configuration

    1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p³

    Electron configuration describes how electrons are distributed in atomic orbitals, showing how they are arranged in energy levels and subshells.