in 1897
Millikan found the charge of an electron by his famous oil drop experiment. J J Thomson determined the specific charge of the electron. That means the ratio of the charge of an electron to its mass. With these two values one can find the mass of electron by dividing the charge value by its specific charge.
The electron has a charge of -1; but the electron has a mass.
Mass and charge are not connected. Negative charge is the charge carried by an electron.
J.J. Thomson discovered that the electron has a very small mass compared to the size of the atom through his experiments with cathode rays in the late 19th century. His work led to the development of the plum pudding model of the atom.
The charge of an electron is -1. Specifically, it is about -1.602 x 10-19 coulombs. The mass of an electron is about 9.109 x 10-31 kilograms, or about one 1836th that of a proton.
The mass of an electron is much smaller than the mass of a proton. An electron has a charge of -1, while a proton has a charge of +1.
Voltaire
Modern Mass Spectrometry is the alternative method to measure the charge to mass ratio of an electron.
A electron is a subatomic particle outside the nucleus carrying a negative charge and very little mass. Other mass is negligible mass or a negative charge.
Compared to the (charge/mass) ratio of the electron:-- The (charge/mass) ratio of the proton is much smaller; although the proton charge is equal to the electron charge, the proton mass is much larger, by a factor of more than 1,800.-- The (charge/mass) ratio of the neutron is zero, because the neutron charge is zero.
J.j. Thomson
He discovered the electron which has a negative charge of 1.602 x 10-19 coulombs and a mass of 9.1 x 10-31 kg.