Sodium is the one of the most abundant elements found on earth. It is a silvery white element comprising 2.6% of the earth’s crust. Sodium is very much essential for our human body in order to maintain fluid balance in our cells. The sodium ions are important for the functioning of our nerve cells. At room temperature, sodium is so soft that it can be cut easily with a blunt knife.
Sodium in its pure form is too reactive. Due to its reactive nature, it is always found in compound form. When it is kept in contact with air, it oxidizes and even catches fire reacting with the moisture in air. That is the reason it is always kept under oil or kerosene. If otherwise it spontaneously reacts with moisture. The reaction between sodium and water produces sodium hydroxide and heat.
The hydrogen produced self-ignites and burns with a flame. The reaction becomes much vigorous when sodium is put in warm water. It causes explosions too.