Occurs with the bonding electron pair remaining intact. Polar reactions (a) usually occur in solution [can occur on polar surfaces], (b) are often catalyzed by acids and bases, (c) often proceed at a rate strongly influenced by the polarity of the solvent, (d) are not affected by light, oxygen, or peroxides (e) are rarely chain reactions. Examples: (a) typical acid/base reactions of inorganic chemistry, (b) solvolysis (the solution process), (c) most organic reactions that occur in solution.