<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> A Lewis acid is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct . A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct . For example, NH is a Lewis base, because it can donate its lone pair of electrons . Trimethylborane (Me B) is a Lewis acid as it is capable of accepting a lone pair . In a Lewis adduct, the Lewis acid and base share an electron pair furnished by the Lewis base, forming a dative bond . In the context of a specific chemical reaction between NH and Me B, the lone pair from NH will form a dative bond with the empty orbital of Me B to form an adduct NH BMe . The terminology refers to the contributions of Gilbert N. Lewis . </P> <P> In many cases, the interaction between the Lewis base and Lewis acid in a complex is indicated by an arrow indicating the Lewis base donating electrons toward the Lewis acid using the notation of a dative bond--for example, Me B ← NH . Some sources indicate the Lewis base with a pair of dots (the explicit electrons being donated), which allows consistent representation of the transition from the base itself to the complex with the acid: </P>

Define the terms lewis acid and lewis base