Period 5 element Klaproth named the new element in 1798 after the Latin word for "earth", "tellus". Gold telluride minerals (responsible for the name of Telluride, Colorado) are the most notable natural gold compounds. However, they are not a commercially significant source of tellurium itself, which is normally extracted as by-product of copper and lead production. Tellurium is commercially primarily used in alloys, foremost in steel and copper to improve machinability. Applications in solar panels and as a semiconductor material also consume a considerable fraction of tellurium production. Iodine is a chemical element with the symbol I and atomic number 53. The name
Chemical element to cause chemical effects), the isotopes of a given element are chemically nearly indistinguishable. All of the elements have some isotopes that are radioactive (radioisotopes), although not all of these radioisotopes occur naturally. The radioisotopes typically decay into other elements upon radiating an alpha or beta particle. If an element has isotopes that are not radioactive, these are termed "stable" isotopes. All of the known stable isotopes occur naturally (see primordial isotope). The many radioisotopes that are not found in nature have been characterized after being artificially made. Certain elements have no stable isotopes and are composed "only" of radioactive