Sodium is a metallic element
with a symbol Na an atomic number of 11. It
has an atomic weight of 22.98976928. 
Things you might not know about
Sodium:
- When Sodium is brought in contact with water,
it explodes,
- Sodium is also used to make vapor lamps,
which are used in street lights. Vapor lamps can produce light from
electricity very efficiently.
- Sodium is the fourth most abundant element
and makes up almost 2.6% of the Earth's crust. It is also
relatively abundant in stars.
- Its symbol, Na, comes from the Latin name
'natrium', which is a common sodium compound.
See GC2XAY2 - Hydrogen, for an explanation
about this series of caches.