A quantum mechanical atom (or quantum-mechanical) is the atom model that illustrates the principles of quantum mechanics, and it is based on the postulates of Erwin Schrödinger, which state that electrons can be treated as waves of matter.
According to Heisenberg’s uncertainty principle, it is not possible to know both the energy and the position of an electron inside the atom. The Schrödinger equation, Ĥψ=Eψ , gives rise to a set of wave functions () that are useful for studying the atom and its elements. The square of the wave function (2) represents the probability of finding an electron in a region of the atom. The region of an atom where there is a probability that the electron will be found 90% of the time is known as an atomic orbital.
The quantum mechanical model of the atom stands in opposition to:
The planetary model, proposed by Ernst Rutherford in 1911, described the atom as a planetary system with a central nucleus around which the electrons would revolve.
Bohr’s atomic model, proposed by Niels Bohr in 1913, is halfway between classical and quantum physics. It was the first model to suggest that electrons can only occupy stable orbits.