Bohr atomic model It attempts to explain how the elements are arranged within an atom. It allowed us to infer that the movement of atoms in circular orbits and their displacement from one orbit to another were capable of producing increases or losses of energy. Here you can learn more about the Bohr's atomic theory.
Atomic Bohr model
It was also called the Rutherford-Bohr model. It was developed in 1913, based on the Rutherford model, which although successful and revolutionary, presented some conflicts with Maxwell's laws and Newton's laws, because it came to the conclusion that all atoms were unstable.
Rutherford's atomic model was based on the fact that moving electrons that had a negative electric charge should propagate electromagnetic radiation, according to the laws of Electromagnetism. Assuming this were so, the loss of energy would cause the electrons to compress their orbit, spiraling toward the center of the atom, and then collapsing into the nucleus.
New ideas
El Bohr atomic model He gave the solution to this problem, arguing that electrons orbit the nucleus, but only in certain permitted orbits and with a certain energy that is proportional to Planck's constant.
These allowed orbits were given the name of energy shells or energy levels. This means that the energy capacity of an electron inside an atom is not continuous, but is quantified at a certain level.
These levels are identified with a quantum number n (n = 1, 2, 3, and more) and according to Bohr, that quantum number could be established using the Ryberg formula, which is a rule created in 1888 by the Swedish physicist Johannes Ryberg to represent the wavelengths of the spectral lines of many chemical elements.
This pattern of energy levels indicated that electrons can only increase or decrease in energy if they manage to jump from one orbit to another, and when this happens, the electron would radiate or absorb electromagnetic radiation in the process.
El Bohr atomic model it was a modification of Rutherford's model. For that reason, the peculiarities of a small central nucleus with most of the mass persisted. In the same way, the electrons carried out their orbital movement around the nucleus, in a similar way to the planets around the sun, but their orbital movements were not flat.
Basic principles of the Bohr atomic model
Particles charged with positive electrical energy are found in very small quantities compared to the volume of the atom and comprise the largest portion of the atom's mass. Meanwhile, electrons, which have a negative electrical charge, move around the nucleus in circular orbits, which already have a predetermined size and energy. Because of this, they do not exist in an intermediate position between the orbits.
The energy of the orbit has a relationship proportional to its size. The lowest energy is found in the orbit with the smallest perimeter. The further away an energy level is from the nucleus, the greater the amount of energy it possesses.
Different energy levels have different numbers of electrons. The lower the energy level, the fewer electrons it has. For example, in level 1 there will be up to 2 electrons, in level 2 there will be up to 8 electrons, and so on. So energy is radiated or absorbed at the moment an electron changes from one orbit to another.
Additional Bohr Atomic Model Considerations
The reason for being Bohr atomic model was to explain that matter remains stable, which previous atomic models did not do, as well as the absorption and irradiation spectra of gases.
Bohr's was the first to use the concept of quantization, which places it between a model of classical mechanics, such as the Contributions by Blaise Pascal and a model of quantum mechanics. He improved it by incorporating discoveries of quantization made by Max Planck a few years earlier and the theories of Albert Einstein.
Despite its shortcomings, the Bohr atomic model was the antecedent to the birth of the quantum mechanics initiated by Schrödinger and other scientists, as well as the Quantum Planck Theory.
Limitations and Errors in the Bohr model
The model does not explain why electrons are uniquely confined to certain orbits.
In the model it was stated that the electrons had a known radius and orbit, which Werner Heisenberg's Uncertainty Principle would disprove ten years later.
El Bohr atomic model it had the ability to reproduce the behavior of electrons in hydrogen atoms, but its patterns were not applicable to atoms of other elements that had larger numbers of electrons.
This atomic model presented inconsistencies when it came to explaining the Zeeman effect. This effect is what can be seen when the spectral lines are divided into two or more, in the presence of an external and immobile magnetic field.
Similarly, the Bohr atomic model supplies an erroneous value for the orbital angular momentum of matter in the ground state.
All these reasons led to the Bohr atomic model It was replaced years later by quantum theory, the product of the scientific work of Heisenberg and Schrödinger.
Who was Niels Bohr?
Niels Bohr was a physicist born in the city of Copenhagen, Denmark, in October 1885. His father was a university professor and his mother was the daughter of a wealthy family. He had the opportunity to enter the University of Copenhagen in 1903, in order to study physics, but he also studied astronomy and mathematics. In the year 1911 he managed to obtain his doctor's degree.
Also in 1911, thanks to having won a scholarship from the Carlsberg Foundation, which dedicated its resources to the study of the atom, he managed to travel to London and during his stay he met relevant scientists, such as JJ Thomson and Ernest Rutherford.
In 1912, he returned to Denmark, marrying Margrethe Norlud, with whom he had six children, one of whom became a renowned physicist who won the Nobel Prize in 1975, just as his father had done years before.
Established in Denmark and due to the unpopularity of physics in his country, he was forced to teach medical students, a fact that displeased Bohr, later returning to Manchester, England, where Rutherford had offered him a position. He remained in London until 2 years after the start of the First World War.
Director of Physics and Nobel Prize
In 1916, he was appointed director of theoretical physics at the University of Copenhagen, a position created especially for him. In 1918, he persuaded the government to establish the Danish Institute for Theoretical Physics, now known as the Niels Bohr Institute, which opened in 1921, with him as its principal director.
He was awarded the Nobel Prize in Physics in 1922 for his work investigating atoms and the radiation they emit. Later, in 1924, Bohr met Heisenberg in Denmark and subsequently had the opportunity to meet with scientists such as Paul Dirac and Erwin Schrödinger, who helped shape the thinking and interpretation of quantum mechanics in Copenhagen.
Bohr died on November 18, 1962 in Carlsberg, Denmark, but he was the father of modern Physics in his country.
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