electrophile
electron-seeking reagants that have room in their orbitals to accept a pair of electrons
nucleophile
reagants seeking a nucleus to which they can donate electrons (most Lewis and Bronsted bases)
nucleophilic substitution/displacement reaction
reaction where a leaving group is detached
leaving group
a stable species that can be detached from a molecule in a bond-breaking step
spectator (counter) ions
ions that appear in the balanced equation for a reaction as support for reagants or products, but don't participate directly in bond-breaking and forming
kinetics
the study of rates of chemical reaction and factors that influence that rate
order
the sum of the exponents of the concentration terms that appear in the rate equation.
transition state
the state lying between reactants and products, with no lifetime but a geometry and charge distribution
activated complex
a molecular complex to describe the transition state, with partial charges, in square brackets with the double dagger symbol
absolute rate constant
(6.2 * 10^12/s) how quickly the activated complex is converted to product at a certain temperature
energy diagram
A diagram that shows the relative energy of the reactants, intermediate state, and products in a chemical reaction
reaction coordinate
x-axis in an energy diagram representing the changes that must take place in bond lengths and bond angles within molecules along the reactant to product conversion
free energy of activation
the height of the energy barrier in a system going from reactants to products - the energy the reactants attain in reaching the transition state
Hammond Postulate
geometry of the transition state most closely resembles the side to which it is closer in free energy
secondary carbocation
a positively charged species with two alkyl groups attached to an electron-deficient carbon atom in the middle
primary carbocation
a positively charged species in which only one alkyl group is attached to the electron-deficient carbon atom
electrophilic addition reaction
a class of reactions where a species is added to a double bond between carbon atoms
regioselectivity
an observed preference in the direction in which molecules interact with one another
reactive intermediates
short-lived, less stable species formed as reactants progress to products