We explain what the Bohr atomic model is, its origin and its main characteristics. Furthermore, the key contributions of this model.
What is the Bohr Atomic Model?
Niels Bohr was a Danish physicist who in 1913 proposed a new model to explain the structure of the atom and its behavior through the stability of the electronsFor this decisive contribution to knowledge he received the Nobel Prize in Physics in 1922.
The model proposed by Bohr worked to understand the functioning of certain types of atoms, such as hydrogen, but not for others with a more complex structure. However, his model opened the doors to establish the following theories and was the basis of the modern atomic model or today.
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Origin of the Bohr atomic model
During the time of ancient Greece It was thought that matter was made up of indivisible principles or elementsthat is, they could not be divided into even smaller parts (like water or air).
However, the work of the chemist John Dalton towards the end of the Modern Age provided the first scientific approaches that laid the foundations of chemical stoichiometry. In 1803 he put forward his atomic theory that matter was composed of atoms of different structures.
In 1897 Joseph Thomson discovered the electron as part of the atom and In 1911 Ernest Rutherford developed a theory on the internal structure of the atom. Niels Bohr was the one who understood and described the organization of those particles called electrons and their distribution in specific orbits around the nucleus of the atom.
Features of the Bohr atomic model
Bohr’s atomic model, which was the basis of the current atomic model, explained the stability of matter and the conformation of chemical bonds. Looking at the graphical representation of the Bohr model will make it easier to understand the following characteristics:
- The electrons surrounding the nucleus of an atom can be internal or external. Both types of electrons are found in circular orbits around the nucleus, but electrons cannot be in all orbits, only those allowed.
- Electrons are in defined energy levels and at fixed distances. The orbit closest to the nucleus has lower energy compared to the orbit farther from the nucleus, which has more energy.
- Orbits have a certain number of electrons, depending on their distance from the nucleus. This distribution scale is called “electron configurations” and is equivalent to the scale of the periodic table (represented in the order of the rows).
- Electrons can jump levels or orbits, and this jump can only occur to and from allowed orbits. For example, an electron that jumps from an outer orbit to an inner one loses energy, which is released in the form of a photon or light. If it jumps from an inner orbit to an outer orbit, it gains energy.
- The minimum amount of energy that can be gained or lost at any wavelength is called “energy quantum”, hence the expression “quantum jump” arises to refer to a change of electrons from one energy level to another. This change is associated with a loss or gain of energy.
Bohr’s main contributions
Bohr’s model was the first to recognize the concept of quantum mechanics in the electronic structure of a hydrogen atom and, furthermore, revealed what the stability of atoms was like.
The classical theory held that an electron (with a negative charge) orbiting around a nucleus (with a positive charge) emitted electromagnetic energy, and lost speed until it fell on the nucleus.
But the experimental tests did not show the process proposed by the classical theory. Based on Bohr’s model and the work of several other physicists, they managed to solve it.
In 1916, German physicist Arnold Sommerfel optimized Bohr’s atomic model. regarding the fact that electrons rotated in circular orbits to add that, in addition, they could rotate in more complex elliptical orbits.
To the concept of quantum mechanics proposed by Bohr, The non-relativistic quantum model of the Austrian physicist Erwin Schrödinger was addedin 1926, whose theory considered electrons as stationary waves of matter that had probability of being in a certain place or another.
In 1927, the German physicists Max Born and Werner Heisenberg contributed to the concept of probability Schrödinger’s Begining of uncertainty, which established that the position and speed of the electron could not be known simultaneously. Therefore, its trajectory could not be known exactly.
Through these general contributions and various studies and theories of other physicists and mathematicians, it was possible to resolve the dilemma posed by classical theory which was unverifiable from experimental tests.
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