Lewis acids and bases ionic bonding. Classically, the term "Lewis acid" is restricted to trigonal planar species with an empty p orbital, such as BR where R can be an organic substituent or a halide. For the purposes of discussion, even complex compounds such as EtAlCl and AlCl are treated as trigonal planar Lewis acids. Metal ions such as Na, Mg, and Ce, which are invariably complexed with additional ligands, are often sources of coordinatively unsaturated derivatives that form Lewis adducts upon reaction with a Lewis base[citation needed]. Other reactions might simply be referred to as "acid-catalyzed" reactions. Some compounds, such as HO, are
Chemical Weapons Convention Chairman of the Norwegian Nobel Committee. The convention distinguishes three classes of controlled substance, chemicals that can either be used as weapons themselves or used in the manufacture of weapons. The classification is based on the quantities of the substance produced commercially for legitimate purposes. Each class is split into Part A, which are chemicals that can be used directly as weapons, and Part B, which are chemicals useful in the manufacture of chemical weapons. Separate from the precursors, the convention defines toxic chemicals as "[a]ny chemical which through its chemical action on life processes can cause death, temporary incapacitation