The Millikan Oil Drop Experiment

How we know the exact charge of a particle that weighs a billionth of a billionth of a billionth of a tenth of a gram includes a F*** You to some haters

Electrons, for being so tiny, are essentially the centerpiece of chemistry. While there are some subdisciplines that more or less ignore it (e.g., nuclear chemistry), the vast majority of chemists’ lives revolve around understanding and manipulating the behavior of electrons. It’s paradoxical really: something that weighs 0.000000000000000000000000000905 grams (9.05*10^(-28) g) influences so much at such a larger scale. Put it this way, one electron is the difference between elemental sodium metal and table salt: one causes a fiery explosion when placed in water, and the other is a delicious seasoning.

Determining the charge on a single electron paved the way for the calculation of other important constants (e.g., Avogadro’s Number), and it marked a significant milestone in the history of chemistry. It was also marked with a bit of controversy, but before we jump into all that, let’s set the stage for this discovery.