What is the X in X-mas?
The symbol for the element xenon.
The symbol for xenon.
A colorless, odorless element in the noble gas group occurring in extremely small amounts in the atmosphere. It was the first noble gas found to form compounds with other elements. Xenon is used in lamps that make intense flashes, such as strobe lights and flashbulbs for photography. Atomic number 54; atomic weight 131.29; melting point -111.9°C; boiling point -107.1°C; density (gas) 5.887 grams per liter; specific gravity (liquid) 3.52 (-109°C). See Periodic Table.