describes what happens in a chemical reaction
Reaction Equation
- a detailed step-by-step description of how a chemical reaction occurs
- sequence of bond-making and bond-breaking steps
- involve the movement of electrons
- provides a rationalization for chemical reactions
- allows one to predict the likely outcome of a reaction
Reaction Mechanism
asymmetrical cleavage of a bond
Heterolytic cleavage
symmetrical cleavage of a bond
Homolytic cleavage
high-energy species carrying an unpaired electron
radical
Heterolytic cleavage
ionic reactions
Homolytic cleavage and radical
radical reactions
- electron-rich, nucleus-seeking reagents
- typically have a negative charge (anions), lone pair, or multiple bonds
nucleophiles
- electron-deficient, electron-seeking reagents
- typically have a positive charge (cations), or are polarizable molecules that
can develop an electron-deficient center
electrophiles
- ions or neutral molecules that are displaced from a reactant as part of
a mechanistic sequence - displacement when a nucleophile attacks an electrophile that carries
a suitable leaving group (C-L)
LEAVING GROUP (L−, L:)
the slowest transformation in the sequence
rate-determining step
dependence of the reaction rate on the concentration of reagents and other variables indicates the number involved in the rate-determining step
rate of reaction
number of reactant molecules involved in the rate-determining step; usually equivalent to the kinetic reaction order
molecularity
cannot be isolated, or even detected; energy maximum
transition state
stable and can be isolated; energy minimum
intermediate
types of organic reactions
substitution
elimination
addition
rearrangement
radical reactions
