Potassium's atomic number is 19 and its symbol is K. Pure potassium is shiny bluish-silver metal. It is about as soft as chilled butter. When potassium is exposed to air it quickly loses its luster and is covered in an oxide layer that is a greyish color. Potassium is very reactive. It catches on fire and explodes when it comes in contact with water shooting out flaming pieces of reacting potassium. In compound form, it is essential to balancing electrical charges in living cells. Potassium was first isolated by dissolving plant ashes in water to make potash. The resulting potash was high in potassium because plants have a significantly higher ratio of potassium to sodium. Modern-day potassium is mined from ancient lakes and seabeds that contain a high concentration of potassium salts and naturally created potash.  

The sample of potassium in this element cube display is encapsulated in an argon-filled glass ampule to prevent the potassium from oxidizing and preserve its shiny luster.