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    He

    Helium

    Noble Gas

    Atomic Number: 2 • Atomic Mass: 4.0026 u • Period: 1 • Group: 18

    Electron Configuration: 1s²
    Phase: Gas
    Electronegativity: 0
    Hydrogen (H)Lithium (Li)
    OverviewPropertiesAtomic StructureOccurrenceApplicationsHistory

    Physical & Chemical Properties

    Physical Properties

    • •Colorless, odorless, tasteless gas
    • •Second lowest boiling point of all elements after hydrogen
    • •Lowest melting point of all elements
    • •Very low solubility in water
    Melting Point

    0.95 K (-272.20 °C, -457.96 °F)

    Boiling Point

    4.22 K (-268.93 °C, -452.07 °F)

    Density

    0.0001785 g/cm³

    Electronegativity

    0 (Pauling scale)

    Chemical Properties

    • •Extremely chemically inert
    • •No stable compounds under normal conditions
    • •Lowest reactivity among all elements
    • •Very high ionization energy

    Electron Configuration

    1s²

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