Atoms have been talked about for over 2000 years. Even before Christ was born, in the Greek era a couple of men called Democritus and Leucippus, these two men were the first people to have come up with the theory of atoms.
The majority of the two Greek men's work has been lost. We only now have the writings of other people that quoted their work. They believed that all matter was composed of atoms and that the atoms could not be split in any possible way into smaller parts.
Leucippus theorised that between atoms there was empty space, if there wasn't any of this empty space and everything was made up of atoms, then how did people grow or how did things change. His theory of empty space was very true because it is proven today that atoms are like vacuums.
The pair also thought that atoms were completely solid and that there could be nothing inside atoms.
This was proven wrong about 1900 years later when Ernest Rutherford discovered the nucleus, which led to the discovery of atoms being mostly empty space.
They thought that atoms were homogeneous, meaning the same all the way through which was proven wrong when electrons were discovered. This showed that the atom had an internal structure; Joseph John Thomson discovered this in 1897.
Democritus believed that atoms are different in both size and shape. He thought that atoms varied their shapes because they were solid and indivisible objects, he thought that they could be rough, concaved shaped and convexed shaped, he believed that they could be anything. He thought that their weight also varied, which is true.
In that time the idea of atoms was preposterous and people strongly opposed the thought of atoms. Therefore because of this atoms were disregarded and...