Discovered "atomos" which is the smallest particle which cannot be destroyed or created which is now known as atom
He discovered that matter is made of atoms and atoms of the same element are identical
He provided evidence that atoms are made of even smaller particles called electrons negatively charged.
he proved the atoms have a nucleus the contains a positive charged particles protons
he discovered that electrons float around the nucleus in a circular path in the electron cloud
he discovered that the nucleus contains uncharged particles known as neutrons