The document traces the development of atomic models from ancient Greek philosophers to modern quantum mechanics. It describes early ideas that atoms were indivisible spheres (Democritus), John Dalton's model of atoms as hard spheres, J.J. Thomson's "plum pudding" model with electrons in a positively charged substance, Ernest Rutherford's discovery of the nucleus from his gold foil experiment, Niels Bohr's model with electrons in specific energy levels around the nucleus, and the modern wave model where electrons exist as probability clouds.

1. Atomic Models: Everything You Need to Know The History of Atomic Theory Miss Reaves 8 th Grade Science

4. Who are these men? In this lesson, we’ll learn about the men whose quests for knowledge about the fundamental nature of the universe helped define our views.

18. Thomson concluded that the negative charges came from within the atom. A particle smaller than an atom had to exist . The atom was divisible! Thomson called the negatively charged “ corpuscles, ” today known as electrons . Since the gas was known to be neutral, having no charge, he reasoned that there must be positively charged particles in the atom. But he could never find them.

28. Wave Model

33. Indivisible Electron Nucleus Orbit Electron Cloud Greek X Dalton X Thomson X Rutherford X X Bohr X X X Wave X X X