This room has been constructed of silvery-white, highly reactive alkali metal. It has one valence electron in its 3rd energy level. While it has some important uses in its metallic form, its major applications are when it forms compounds with other elements. When paired with chloride it is used for anti-icing and de-icing and as a preservative.

 

If you think you know what it is, carve its symbol in your journal and try to open the lock using it.