Xenon was discovered in England by the Scottish chemist William Ramsay and English chemist Morris Travers on July 12, 1898, shortly after their discovery of the elements krypton and neon. They found xenon in the residue left over from evaporating components of liquid air.
Atomic number: 54
Atomic weight: 131.29
Group, period, block: 18, 5, p
Color: colorless gas
Classification: noble gases
Electron configuration: 5s2 4d10 5p6
Density: 5.894 g/L
Melting point: 161.4 K, -111.7 °C, -169.1 °F
Boiling point: 165.03 K, -108.12 °C, -162.62 °F
Oxidation states: 0, +1, +2, +4, +6, +8
Electronegativity: 2.6 (Pauling scale)
Ionization energies: 1st: 1170.4 kJ·mol-1
Covalent radius: 140±9 pm
Van der Waals radius: 216 pm
There are nine naturally occurring isotopes of xenon exist, 124Xe, 126Xe, 128Xe, 129Xe, 130Xe, 131Xe, 132Xe, 134Xe, and 136Xe.