Sodium was used as a headache remedy by in the medieval times. It evaporates immediately on exposure to air. It reacts violently with water. Sodium is only found in nature in the combined state. It is mostly found in the ocean and salt lakes as sodium chloride, and sometimes found as sodium carbonate and sodium sulfate.
Sodium is a very reactive element.
It may or may not ignite water all the time. Though it normally does ignite in air temperatures below 115 degrees C. Metallic sodium is vital in the manufacture of esters. Sodium is in table salt as part of a compound. It is also in streetlights as a pure element and in batteries as an alloy. Sodium is found in as an alloy in nuclear reactor coolant.