Sodium is the 11th element in the Periodic Table and has Na for the symbol (from the Latin Natrium). Sodium was isolated by Sir Humphrey Davy in 1807 from the alkaline compound sodium hydroxide.
Sodium has 11 protons and electrons in total, and it has a mass number of 23, meaning that it has 12 neutrons. Pure sodium is a soft and silvery metal. Sodium is prevented from contact with the air and water by immersion in oil, because it tarnishes very quickly when exposed to air. It is so soft that you could cut it with a butter knife. A positive flame test for Sodium would give out a vivid yellow color.
Sodium has several compounds. The most common is sodium chloride (HaCl), which has one sodium and one chlorine atom. Sodium Chloride is commonly known as Table Salt. Other sodium compounds include baking soda (NaHCo3) and the alkali Sodium Hydroxide (historically known as lye) with the formula NaOH.
Sodium is highly reactive and may ignite on contact with water. It will even cause an explosion and cause sodium hydroxide to be formed. Sodium Hydroxide is a very strong alkaline that is corrosive and should not be touched.