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    Ac

    Actinium

    Actinide

    Atomic Number: 89 • Atomic Mass: 227.0000 u • Period: 7 • Group: 3

    Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 6d¹
    Phase: Solid
    Electronegativity: 1.1
    Radium (Ra)Thorium (Th)
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    Physical & Chemical Properties

    Physical Properties

    • •Silvery-white radioactive metal
    • •Glows blue in darkness due to radioactivity
    • •Relatively soft for a metal
    Melting Point

    1323 K (1049.85 °C, 1921.73 °F)

    Boiling Point

    3471 K (3197.85 °C, 5788.13 °F)

    Density

    10.07 g/cm³

    Electronegativity

    1.1 (Pauling scale)

    Chemical Properties

    • •Forms Ac³⁺ ions in solution
    • •Oxidizes quickly in air
    • •More electropositive than lanthanides

    Electron Configuration

    1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 6d¹

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