Chemistry: A Volatile History exactly what Mendeleev would predict for an element that sits directly beneath liquid mercury in the periodic table. It aired in the United States under the title "Unlocking the Universe." The full series was released as a region 2 DVD set in 2015 by the Dutch company B-Motion. 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
Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the