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
Cobalt boride Cobalt boride nanoparticless in the size range of 18 to 22 nm have also been produced. When used as a catalyst, cobalt boride is prepared by reducing a cobalt salt, such as Cobalt(II) nitrate, with sodium borohydride. Prior to reduction, the surface area of the catalyst is maximized by supporting the salt on another material; often this material is activated carbon. Cobalt boride Cobalt borides are inorganic compounds with the general formula CoB. The two main cobalt borides CoB and CoB. These are refractory materials. Cobalt boride is known to be exceptionally resistant to oxidation, a chemical property which makes