Quantum theory is also known as quantum mechanics or quantum physics, and its main focus of study is the microscopic world.
The principles of energy quantization, proposed by Einstein and Planck, and experimental observations of the atomic spectrum of elements showed that Newton’s laws did not produce correct results when applied to very small systems, such as atoms and molecules.
To explain the movement of electrons around the nucleus a new theory was created – by Planck, Bohr, Einstein and Schrodinger – Quantum Mechanics.
Despite its enormous success, Bohr’s theory had several shortcomings. The spectrum of more complex atoms could not be explained, raising questions such as: why are some rays in the spectrum more intense than others? And, above all, how do atoms interact with each other to form stable systems?
In the year 1911, Rutherford proposed an atomic model in which electrons (e-) circled the positively charged nucleus, analogously to the movement of planets around the Sun. Although it was simple and coherent, this model had an uncorrectable error, for every particle describing a circular motion has acceleration. In this way, as Maxwell had explained through his equations, due to acceleration the electron should emit light, gradually losing energy until it collides with the nucleus.
Bohr, building on the concepts of quantization, stipulated that the energy of electrons in their orbits around the nucleus was also quantized. That is, in an atom like hydrogen there are several possible stable orbits for the electron, each with different energy. So he was able to correct Rutherford’s model.
But it wasn’t until the work of Erwin Schrodinger and Werner Heisenberg in 1925 that quantum theory became established. Schrodinger postulated an equation that made it possible to calculate energy levels and the probability of finding a particle in a given region.
By Newton’s Laws, we can describe the movement of electrons (position and velocity) from the forces that act on them. Quantum Theory, in turn, calculates the probability of finding an electron (or other particle) in a region of space, using the Schrodinger equation.
Don’t stop now… There’s more after the publicity 😉
By Domitiano Marques
Graduated in Physics
Team