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    Tl

    Thallium

    Post Transition

    Atomic Number: 81 • Atomic Mass: 204.3800 u • Period: 6 • Group: 13

    Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p¹
    Phase: Solid
    Electronegativity: 1.62
    Mercury (Hg)Lead (Pb)
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    Physical & Chemical Properties

    Physical Properties

    • •Soft, bluish-white metal
    • •Malleable
    • •Can be cut with a knife
    Melting Point

    304 K (30.85 °C, 87.53 °F)

    Boiling Point

    1473 K (1199.85 °C, 2191.73 °F)

    Density

    11.85 g/cm³

    Electronegativity

    1.62 (Pauling scale)

    Chemical Properties

    • •Highly toxic
    • •Tarnishes in air
    • •Forms compounds in +1 and +3 oxidation states

    Electron Configuration

    1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p¹

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