Oxygen ( O )

• Atomic number: 8
• Appearance: colorless gas
• Standard atomic weight: 15.999
• Group: group 16 (chalcogens)
• Period: 2
• Electron configuration: 1s² 2s² 2p⁴
• Element category: reactive nonmetal
• Melting point: 54.36 K
• Boiling point: 90.188 K
• Sublimation point:
Standard Temperature ( 273.15 ) and Pressure ( 1 bar = 10⁵ Pa )
• Phase at STP: ( O₂ ) gas
• Density at STP:
• Heat of fusion: ( O₂ ) 0.444 kJ/mol
• Heat of vaporization: ( O₂ ) 6.82 kJ/mol
• Molar heat capacity: ( O₂ ) 29.378 kJ/(mol·K)
• Oxidation states: −2, −1, 0, +1, +2
• Electronegativity: Pauling scale: 3.44
• Covalent radius: 66 pm (1×10⁻¹² m)
• Van der Waals radius: 152 pm (1×10⁻¹² m)
• Crystal structure: cubic
• Speed of sound: 330 m/s m/s (gas, 27 °C)
• Thermal expansion:
• Thermal conductivity: 0.02658 W/(m·K)