Chemical element or an electrophile; similarly "Nu" denotes a nucleophile. "L" is used to represent a general ligand in inorganic and organometallic chemistry. "M" is also often used in place of a general metal. At least two additional, two-letter generic chemical symbols are also in informal usage, "Ln" for any lanthanide element and "An" for any actinide element. "Rg" was formerly used for any rare gas element, but the group of rare gases has now been renamed noble gases and the symbol "Rg" has now been assigned to the element roentgenium. Isotopes are distinguished by the atomic mass number (total protons and
Element Hunters Element Hunters In the year 2029, chemical elements such as oxygen, carbon, gold, molybdenum, and cobalt were continually disappearing from Earth. These disappearing elements ultimately disrupted the environment and led to the destruction of various homes, cities, and even entire countries. Researchers discovered that the vanishing elements drained into a planet called Nega Earth, located in another dimension. Element dematerialization was occurring rapidly; thus, to save Earth, three special pre-teens picked by the space colony government formed the Element Hunters. Their job was to transport themselves to Nega-Earth to battle monsters called Q-EXes and retrieve lost elements. However, out of