The wave-particle duality of light was demonstrated first with Thomas Young's 1801 Interference Experiment...and then more clearly with the Double Slit Experiment. Both of these were done with light (so photons). My question is -- How did we come to understand the same of electrons? Did we manage to "pick an electron" off of an atom and attempt the experiment with it? When and how was the wave-particle duality of electrons demonstrated? As far as I've understood...electrons have a mass and a charge, wheres photons have no mass and no charge, so their properties are different.