Bohr atomic model

Bohr

Surely you have ever seen the Bohr atomic model. This is quite an important discovery that this scientist made for science, especially electromagnetism and electrochemistry. Previously there was the Rutherford model, which was quite revolutionary and very successful, but there were some conflicts with other atomic laws such as Maxwell's and Newton's.

In this article we are going to tell you everything you need to know about Bohr's atomic model, as well as its details to clarify any doubts on the subject.

Problems it helped solve

Energy levels

As we mentioned at the beginning of the article, this atomic model helped resolve certain conflicts that existed with other atomic laws. In the previous Rutherford model, we had to electrons moving with a negative electrical charge had to emit a type of electromagnetic radiation. This should be fulfilled due to the laws of electromagnetism out there. This loss of energy causes the electrons to be reduced to their orbit moving in a spiral towards the center. When they reached the center they collapsed, colliding with the core.

This generated a problem in theory since it could not collapse with the nucleus of the atoms, but the trajectory of the electrons had to be different. This was solved with the Bohr atomic model. It explains that the electrons orbit around the nucleus in certain orbits that are allowed and that have a specific energy. Energy is proportional to Planck's constant.

These orbits that we have mentioned where the electrons move, were called energy layers or energy levels. That is, the energy that electrons have is not the same always, but is quantized. Quantum levels are the different orbits in which atoms are. Depending on which orbit it is in at any given moment, it will have more or less energy. The orbits closer to the nucleus of the atom have a greater amount of energy. On the other hand, the more they move away from the nucleus, the less energy.

Energy level model

Electrons orbiting

This Bohr atomic model, which implied that electrons could only gain or lose energy by jumping from one orbit to another, helped to solve the collapse proposed by Rutherford's model. When moving from one energy level to another, it absorbs or emits electromagnetic radiation. That is, when you jump from a more charged energy level to a less charged one, you release the excess energy. Conversely, when it goes from a low energy level to a higher one, it absorbs electromagnetic radiation.

As this atomic model is a modification of the Rutherford model, the characteristics of the small central nucleus and with most of the mass of the atom are maintained. Although the orbits of the electrons are not flat like those of the planets, it could be said that these electrons rotate around their nucleus in a similar way to the planets do around the Sun.

Bohr's atomic model principles

Bohr atomic model

We are now going to analyze the principles of this atomic model. It is about a detailed explanation of said model and its operation.

  1. Particles that have a positive charge They are in low concentration compared to the total volume of the atom.
  2. Electrons with a negative electrical charge are those that are found rotating around the nucleus in circular orbits of energy.
  3. There are energy levels of the orbits through which the electrons circulate. They also have a set size, so there is no intermediate state between orbits. They just go from one level to another.
  4. The energy that each orbit possesses is related to its size. The further the orbit is from the nucleus of the atom, the more energy it has.
  5. Energy levels have different numbers of electrons. The lower the energy level, the fewer electrons it contains. For example, if we are at level one, there will be up to two electrons. At level 2, there can be up to 8 electrons, so on.
  6. When electrons move from one orbit to another, they absorb or release electromagnetic energy. If you go from one more energetic level to another less, you release excess energy and vice versa.

This model was revolutionary and tried to give a stability to the material that the previous models did not have. The discrete emission and absorption spectra of the gases were also explained with this atomic model. It was the first model that introduced the concept of quantization or quantization. This makes Bohr's atomic model to be considered as a model that is halfway between classical mechanics and quantum mechanics. Although it also has shortcomings, it was a precursor model for the later quantum mechanics of Schrödinger and other scientists.

Limitations and errors of the Bohr atomic model

Full atom

As we have mentioned, this model also has certain shortcomings and errors. First of all, it does not explain or give reasons why electrons have to be limited only to specific orbits. It directly assumes that electrons have a known radius and orbit. However, this is not so. A decade later Heisenberg's uncertainty principle disproved this.

Although this atomic model was able to model the behavior of electrons in hydrogen atoms, it was not so exact when it comes to elements with a higher number of electrons. It is a model that has trouble explaining the Zeeman effect. This effect is what can be seen when the spectral lines are divided in two or more in the presence of an external and static magnetic field.

Another of the errors and limitations that this model has is that it provides an incorrect value for the angular momentum of the ground state orbit. All these errors and limitations mentioned make that Bohr's atomic model was replaced by quantum theory years later.

I hope that with this article you can learn more about Bohr's atomic model and its applications in science.


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