Democritus' model of the atom was simply a round, solid ball. Democritus knew nothing of separate protons, neutrons and electrons; all he knew was that everything physical was composed of atoms, according to Boise State University. Democritus concluded, "Nothing exists except atoms and empty space."
Before the Democritus model, ancient philosophers believed that everything was made up of either earth, wind, water or fire. Around 400 B.C., Democritus created this first model of the atom, believing that the atom was the smallest particle of matter. Democritus theorized that atoms are solid, indestructible and unique. He created the name "atom" from the Greek word "atomos," which means "uncuttable."