Ele018 - Argon - (Elements Series) Traditional Cache

Argon is a chemical element represented by the symbol Ar. Argon has an atomic number of 18.  It has an atomic weight of 39.948. 

Things you might not know about Argon:

1. Commonly used to fill light bulbs, as it does not react with the hot filament.
2. Argon, a colorless and odorless gas, makes up 0.93% of our planet’s atmosphere.
3. It is used for thermal insulation in energy efficient windows.

See GC2XAY2 - Hydrogen, for an explanation about this series of caches.