Boron: In Search of the Real Fifth Element

Classical alchemy divided matter into just four elements, although some argued for the recognition of a fifth element. Modern chemistry divides matter into a whole array of elements, commonly known as the periodic table. In this table boron is the fifth element, and it sits right at the intersection of many classes of elements; between the metals and the non-metals; between those with just the right number of electrons for bond formation, and those with far too few; between those that form bonds by sharing electrons, and those that give them away.