Chemestry Histoy of an Atom

History of an Atom: 

At the begining of the 19th century John Dalton described atoms as solid spheres, and said that different spheres made up the different elements. 

In 1887 J.I  Thompson concluded from his ecperiments that atoms weren't solid spheres. His measurments of charge and mass showed that an atom must contain even smaller, negatively charged particles - electrons. 

The solid sphere idea of the atomic structure had to be changed. The new theory was known as…