How was sodium discovered?

Sodium was first isolated in 1807 by Humphrey Davy, one of the early luminaries of modern chemistry. The element was found, along with potassium, when Davy electrolyzed damp potash with soda. Prior to his discovery, these compounds were thought to be elements themselves, as they resisted decomposition.

Sodium is the sixth most common element on Earth. It does not occur in its pure form owing to its highly reactive properties. Once isolated, sodium must be kept away from water or it ignites. This reactivity made sodium relatively difficult to find, as well as difficult to handle, with early 19th-century methods.