Period 3 element phosphorus originates from oxidation of the white (but not red) phosphorus and should be called chemiluminescence. It is also the lightest element to easily produce stable exceptions to the octet rule. The vast majority of phosphorus compounds are consumed as fertilizers. Other applications include the role of organophosphorus compounds in detergents, pesticides and nerve agents, and matches. "Sulfur" (symbol S) is an abundant, multivalentnon-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S. Elemental sulfur is a bright yellow crystalline solid when at room temperature. Chemically, sulfur can react as either an oxidant or reducing agent.
Chemical element neutrons) for a particular isotope of an element, with this number combined with the pertinent element's symbol. IUPAC prefers that isotope symbols be written in superscript notation when practical, for example C and U. However, other notations, such as carbon-12 and uranium-235, or C-12 and U-235, are also used. As a special case, the three naturally occurring isotopes of the element hydrogen are often specified as H for H (protium), D for H (deuterium), and T for H (tritium). This convention is easier to use in chemical equations, replacing the need to write out the mass number for each atom.