Origin and use of the term metalloid antimony and tellurium, was recorded merely on a 'sometimes' basis. Use of the term metalloid subsequently underwent a period of great flux up to 1940. Consensus as to its application to intermediate or borderline elements did not occur until the ensuing years, between 1940 and 1960. In 1947, Pauling included a reference to metalloids in his classic and influential textbook, "General chemistry: An introduction to descriptive chemistry and modern chemical theory." He described them as 'elements with intermediate properties ... occupy[ing] a diagonal region [on the periodic table], which includes boron, silicon, germanium, arsenic, antimony, tellurium, and polonium.' In 1959
Boron the oldest leaves and black spots in barley leaves, but it can be confused with other stresses such as magnesium deficiency in other plants. Boron Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar system and in the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known boron deposits are in