Sodium is an element that is a member of the alkali metal group with a symbol Na. It is physically silver colored and is a soft metal of low density. Pure sodium is not found naturally on earth because it is a highly reactive metal. The sodium ion is abundantly found within the Earth's oceans, bodies of water, and many minerals. It is used for chemical synthesis, analysis, and heat transfer applications. Sodium is also a crucial element for animal and plant life by creating charge gradients and assisting in the development of energy. 

Sodium was discovered and isolated in 1807 by Sir Humphry Davy. In its pure form it is silvery white and soft enough to cut with a knife. It is the sixth most abundant element in the earth's crust, occurring in large amounts in both (sea)water and soil in various mineral compounds, the most common of which is sodium chloride.