________ step in the sequence of elementary reactions determines the measured reaction rate.

_______ is an electron - pair acceptor that reacts at centers of high electron density.

________ is the rate of change of concentration of a particular reactant or product over a very small time interval.

_________ takes place when one of the atoms gains both electrons farming the bond.

_____ collision is one which occurs between molecules which possess enough energy to cross the energy barrier and which are properly oriented with respect to each other.

If two molecules of reactants are involved in a step of reaction, then the molecularity of that reaction is