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    H

    Hydrogen

    Nonmetal

    Atomic Number: 1 • Atomic Mass: 1.0080 u • Period: 1 • Group: 1

    Electron Configuration: 1s¹
    Phase: Gas
    Electronegativity: 2.2
    Helium (He)
    OverviewPropertiesAtomic StructureOccurrenceApplicationsHistory

    Physical & Chemical Properties

    Physical Properties

    • •Colorless gas at standard temperature and pressure
    • •Lowest density of all gases
    • •Becomes liquid at -252.87°C
    • •Can diffuse through many materials including metals
    Melting Point

    14.01 K (-259.14 °C, -434.45 °F)

    Boiling Point

    20.28 K (-252.87 °C, -423.17 °F)

    Density

    0.00008988 g/cm³

    Electronegativity

    2.2 (Pauling scale)

    Chemical Properties

    • •Highly flammable and forms explosive mixtures with air
    • •Reacts with oxygen to form water
    • •Can act as a reducing agent
    • •Forms compounds with most elements

    Electron Configuration

    1s¹

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