sentence: Sodium is so soft that it can be easily cut with a knife.
sentences_before: Sodium is a light, silver-coloured metal.
sentences_after: When it is cut, the surface will become white after a bit of time. This is because it reacts with air to form sodium hydroxide and sodium carbonate. This reaction is very fast. Hydrogen and sodium hydroxide are produced. The hydrogen may ignite.
concept_name: sodium
headings: Sodium Properties
categories: Alkali metals Chemical elements