This tile identifies the data on the other tiles. In case it's not obvious, here's a key to the key:
|Name (American spellings)
|Density in grams per cubic centimeter (I don't have small lowercase letters....)
Elements that are gases have their density in grams per liter, which is marked on the individual tile.
|Melting point in degrees Centigrade
|Boiling point in degrees Centigrade