In the 1920s, Erwin Schrödinger proposed that electrons travel in waves, which means their exact positions cannot be determined. Using his equation, he identified regions around the nucleus, called orbitals, where electrons are most likely to be. Orbitals are the basis of the electron cloud model of the atom.

Electron cloud is an informal way to describe an atomic orbital. The electron cloud model says that we cannot know exactly where an electron is at any given time, but the electrons are more likely to be in specific areas. These areas are specified by orbitals. The orbitals are specified by shells and sub-orbitals.

the quantum mechanical model of the atom
Erwin Schrödinger proposed the quantum mechanical model of the atom, which treats electrons as matter waves.

1926
Atomic Theory. Austrian physicist Erwin Schrödinger (1887-1961) developed an “Electron Cloud Model” in 1926. It consisted of a dense nucleus surrounded by a cloud of electrons at various levels in orbitals.

Max Planck
Francis CrickKarl PopperJames D. WatsonHugh Everett III
Erwin Schrödinger/Influenced

Rutherford model, also called Rutherford atomic model, nuclear atom, or planetary model of the atom, description of the structure of atoms proposed (1911) by the New Zealand-born physicist Ernest Rutherford.

When passed between the poles of a magnet, these cathode rays behave the same way as the β particles described earlier. The fact that they were very small electrically charged particles led the English physicist J. J. Thomson (1856 to 1940) to identify them with the electrons of Faraday’s experiments.