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 safety assessment the European Chemicals Agency as part of the respective registration dossier. The purpose is to ensure that the risks related to the substance are controlled. The chemical safety assessment of a substance comprises the following steps: The European Chemicals Agency (ECHA) has developed a software tool to support industry in preparing a Chemical Safety Assessment (CSA) and Chemical Safety Report (CSR). Chesar Beta version can be downloaded from the Chesar website. Chemical Safety Reports are the main end point for data assessment under REACH (the European Community Regulation on chemicals and their safe use, concerning the Registration, Evaluation, Authorisation and