jan 1, 1904 - JJ Thomson's Atomic Theory
In 1904, Thomson created a model called the "Plum Pudding Model." This model consisted of a spherically shaped atom composed of uniformly distributed positive charge in which the negatively charged electrons resided. He created this model after experimenting with a cathode ray tube to find that electrons were negative.
Added to timeline:
Atomic Theory Timeline - Adrianne Moran 4th Period Chemistry