There are over 100 elements in the universe, of which 81 are metals. In this Pupil Programme, Science teacher Subathra Subramaniam explores some of these, explains the usefulness of the Periodic Table and discovers why some elements are more reactive than others. At Portobello Market in London she learns why gold, silver and copper are ideal for making jewellery and what properties they have in common. Subathra then examines the alkali metals, which are the most reactive and are found in group 1 of the Periodic Table. She looks at their characteristics, reactions and uses. She also explores the halogens, a group of non-metals, found in group 7 of the Periodic Table, which display their own qualities and trends. Professor Holloway of Leicester University, an expert on fluorine, the most reactive of these non-metals, demonstrates just how nasty it can be. He shows how each of the halogens reacts with hydrogen, and we learn there’s a surprising number of good uses for halogens.