Lewis acids and bases factors, in addition to electron configuration factors, play a role in determining the strength of the interaction between the bulky di-"t"-butylpyridine and tiny proton. Lewis acids and bases 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
CSX milepost prefixes CSX milepost prefixes Most CSX railroad lines are given lettered prefixes before milepost numbers. These prefixes are one to three letters long with the first letter usually refer to the former company. For instance, prefixes beginning with "S" were part of the Seaboard Air Line Railroad. Some of these company prefixes include the following: Lines that were formerly part of the Atlantic Coast Line Railroad system are given milepost prefixes beginning with the letter A. For instance, milepost A790 is on the main line in Orlando, Florida, 1000 miles south of the beginning in Richmond, Virginia, and milepost AN587 is