helium

2. Helium

   Topic covered :-

    Helium

    Hellium atom

   All details of Hellium

   Helium gas

• Symbol: He

• Atomic number:2

• Mass: 4.0026 g/mol

• Discove by: Pierre Jules césar janssen joshep Norman Lockyer

• Year:1895

• Electro: 2  Proton: 2  newton: 0

Image

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• Melting point: -272.2°C

• Boiling point: -268.8°C

• Density: 0.000178 g/cm³

• Phase: Gas

• Electron configuration: 1s²

• Atomic radius: 31pm

• Crystal structure: Hexagonal close packed