xenon

1. N a colourless odourless gaseous element occurring in trace amounts in air; formerly considered inert it is now known to form compounds and is used in radio valves, stroboscopic and bactericidal lamps, and bubble chambers. Symbol: Xe; atomic no: 54; atomic wt: 131.29; valency: 0; density: 5.887 kg/m3; melting pt: –111.76°C; boiling pt: –108.0°C 氙