Very high purity of 99.95 per cent, sealed in glass. Sodium is a silver-white cubic structure of the metal, soft and light, can be cut with a knife, the density is smaller than water, 0.968g/cm3, melting point 97.72 ℃, boiling point of 883 ℃. Sodium is one of the most reactive metallic elements in the periodic system and is highly reactive. Sodium is a metallic element with the symbol Na. It is located in Period 3, Group IA in the Periodic Table and is a representative of the alkali metal elements. It is soft in texture, reacts with water to form sodium hydroxide, which releases hydrogen gas and is chemically more reactive.