Chemistry: A Volatile History Chemistry: A Volatile History Chemistry: A Volatile History is a 2010 BBC documentary on the history of chemistry presented by Jim Al-Khalili. It was nominated for the 2010 British Academy Television Awards in the category Specialist Factual. Only in the last 200 years have we known what an element is – a substance that cannot be broken down further by chemical reaction. The Ancient Greeks, with no way of breaking open substances, could only base their ideas of the elements on what they could see: Earth, Fire, Water and Air. In the 16th century alchemists were busy trying to turn
Chemical substance regard. A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook. According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties. The chemical substance index published by CAS also includes several alloys of uncertain composition. Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for