An electrophile is a reagent that takes away an electron pair. In other words, an electron-seeking reagent is called an electrophile (E+). Electrophiles are electron-deficient and can receive an electron pair.
Carbocations \((CH_3CH^+_2)\) and neutral molecules having functional groups such as the carbonyl group (
) are examples of electrophiles.
A nulceophile is a reagent that brings an electron pair. In other words, a nucleus-seeking reagent is called a nucleophile (Nu:).
For example: OH-, NC- , carbanions (R3C-), etc
Neutral molecules such as H2Ã- and ammonia also act as nucleophiles because of the presence of a lone pair.
The reaction sequence given below is carried out with 16 moles of X. The yield of the major product in each step is given below the product in parentheses. The amount (in grams) of S produced is ____. 
Use: Atomic mass (in amu): H = 1, C = 12, O = 16, Br = 80
Two identical ball bearings in contact with each other and resting on a frictionless table are hit head-on by another ball bearing of the same mass moving initially with a speed V. If the collision is elastic, which of the following (Fig. 5.14) is a possible result after collision ?

SN1 reaction mechanism takes place by following three steps –
The SN2 reaction mechanism involves the nucleophilic substitution reaction of the leaving group (which generally consists of halide groups or other electron-withdrawing groups) with a nucleophile in a given organic compound.
The mechanism of an electrophilic aromatic substitution reaction contains three main components which are:
The electrophilic substitution reaction mechanism is composed of three steps, which will be discussed more below.