The elementary charge, also known as the fundamental unit of charge, is the electric charge carried by a single proton or electron. It is the smallest unit of electric charge that can exist in isolation.
The symbol for elementary charge is "e".
The numerical value of elementary charge is approximately 1.602 x 10^-19 Coulombs.
The value of elementary charge was first determined by physicist Robert Millikan in his famous oil drop experiment in 1909. He observed the movement of charged oil droplets in an electric field and calculated the charge on each droplet, which was found to be a multiple of the elementary charge.
The elementary charge plays a crucial role in the atomic structure as it determines the charge of subatomic particles such as protons and electrons. In an atom, the number of protons and electrons are equal, resulting in a neutral charge. This balance of positive and negative charges is what holds the atom together.