In the midst of a knowledge society, science is one of the fields that is advancing faster and making the greatest progress. Throughout history people began to believe less in myths such as reading the palm. Currently having vaccines for practically all diseases has been possible thanks to the work carried out by numerous experts and scientists. One of them is Friedrich Hund, a well-known physicist who dedicated his professional career to the investigation of everything related to molecules and atoms. One of his best discoveries was none other than the well-known Hund rule, which is obtained from the exhaustive study that he carried out of all the elements of the periodic table, and above all their situation and order in which they are established..
What is Hund’s rule?
To understand Hund’s rule, developed by Friedrich Hund, it is necessary to have a minimum knowledge of chemistry, starting with knowing the definition of an atom and also its main particles. Without it, it is impossible to understand the periodic table since each element in this table is made up of protons, neutrons and electrons, the main elements of the atom. When we speak at a material level, the atom is considered as the smallest substance. It has been one of the great investigations that has been carried out throughout history. In fact, it began in Greek times by Democritus and Leucippus, two intellects who began to suspect that all the matter around us could contain both divisible and indivisible matter. Over the years and centuries, multiple theories related to the world of atoms began to emerge until reaching the current theory. An atom is composed of a nucleus that forms the central part. Within this nucleus we can find two types of particles. These are the protons that are the ones that have a type of charge that is positive, together with the neutrons that have a neutral charge.
In addition, in its external part, we find the crown of the atom that is composed of all the electrons that make up all the negative part at the level of charge that can be found. In high school, students must learn all the elements of the periodic table throughout their Compulsory Secondary Education. In this table, you will find each element together with its atomic number, expressed with the letter Z, and which explains the number of protons that we can find in the nucleus of the atom itself. On the other hand, the letter A can also be present in the nucleus of the atom itself. This means the atomic mass by adding the total number of protons and neutrons that we can find in the same nucleus. Among the atomic science we must differentiate what is known as isotopes. This differentiation occurs when the same number of protons are found in an atom but, on the other hand, the number of neutrons is not exactly the same. Despite this, the way of interpreting these atoms does not change since their behavior depends exclusively on the number of neutrons and electrons. Radioactivity, on the other hand, has been the cause of numerous environmental problems. In fact, the property of atoms is the cause of many radioactive problems since the higher its atomic mass (ie the letter A), the greater the possibility of radiation. When this happens, these atoms decompose, acquiring another type of atomic mass.
For example, uranium is one of the clearest examples. This material is one of the most used in nuclear power plants. Its atomic mass reaches number 238. However, through successive decompositions, it can reach radius 226, which is the one that coincides with lead. Therefore, the radiation of atoms is another of the properties that we must take into account. The study of the atomic table is one of the heaviest subjects for many students, and one of the favorites to end up doing a cheat sheet for the number of numbers that it is necessary to memorize in order to pass this exam. However, going back to Hund’s rule, these basic concepts are necessary to be able to understand what the German physicist Friedrich Hund proposed centuries ago. Orbitals are the space that an atom contains and, according to Hund, when these orbitals contain this same energy, the electrons tend to be distributed in an angular and more proportionate way. When this occurs, Hund proposed that the entire atomic configuration surrounding the atom will tend to have greater stability.
This same Hund rule was also explained through the logical numbering of Hund’s multiplicity, which comes to explain the same previous rule but altering the order of the factors. As in the commutative property, the order of the factors does not change the product. Therefore, when the electrons are distributed in an unpaired way, that is, forming an angle, the orbitals are also distributed in this unpaired way and, therefore, said stability in atoms is achieved. This general explanation by Friedrich Hund is complemented by three general rules that must be applied when studying any type of atom:
- Total spins and their value is inversely proportional to the energy value of the atom. In this way, the higher the spin, the lower the energy of the atom and vice versa. The higher the energy of the atom itself, the higher the spin.
- In accordance with the spins, the lower the energy value of the atom, the higher the number L that corresponds to it .
- On the other hand, when we refer to the atom from a spectroscopic point of view, the J number is correctly proportional to its J number, always taking into account the shell or the outermost part of the nucleus of the atom itself.
The main principle of this Hund’s rule is that all the space of the atom must be occupied and, consequently, each electron found in the molecule must have the ability to have a subshell in which each of the electrons are aligned. electrons to get to have that angular shape.
Benefits of Hund’s Rule
All in all, Hund’s rule was an enormous advance in terms of the study of the molecules of atoms for the field of physics and chemistry. The most prominent are:
- Promote research. All the work carried out by professionals such as Friedrich Hund has allowed scientific progress that has favored the work they are doing to continue scientific progress towards surgical interventions that favor today’s society.
- Advances in chemistry. The work carried out in the laboratories may seem silly or go unnoticed by many. However, it has allowed the creation of products, or have biological utilities that favor technological and health progress.
- Understand the atom. Atoms, as we have said before, are the smallest molecules that matter has and therefore understanding them makes it easier to advance in many areas of knowledge other than chemistry and physics. It also allows experiments with children.
- Promote nuclear energy. Despite disasters such as those that occurred in Russian territory in Chernobyl and its nuclear power plant, uranium and its molecular knowledge have facilitated procedures such as nuclear fission, enabling the production of electrical energy.
Who was Friedrich Hund?
Friedrich Hund was one of the best known physicists of the 20th century. His training was exceptional, finishing university degrees in physics, mathematics and geography. This provided him with knowledge divided into different branches that enabled him to obtain different aspects to end up carrying out his Hund’s rule. In addition to research, he was also a professor at different universities around Germany such as Leipzig, Rostock and also in the capital of Denmark, Copenhagen. This university teaching also allowed him to update all the knowledge that he later used to make Hund’s rule.
In addition, he published hundreds of scientific books and articles in science-related magazines and media. This résumé only does more than highlight the enormous preparation that Friedrich Hund had, who completely dedicated his life to science. In addition, he did it in a country that was the protagonist of the history of the 20th century. Initially, it participated in two World Wars and was dominated by the Nazi regime where scientific advances went more unnoticed. Subsequently, for decades they waged a cold war between the capitalist side and the communist side, which did nothing more than divide Germany in two over a Berlin wall that was not torn down until 1989. Undoubtedly, some elements that only magnify the work of Friedrich Hund.
Hund’s rule serves as a complement to other types of theories of other scientists, such as the Aufbau Principle, formulated by Niels Bohr. This is also a special case because he is one of the few researchers who did not put his name to his discovery. Instead of naming him Bohr as Hund, he used the German word construction to name him the principle of construction in our language. As described by Hund’s rule, the electrons are located in an orderly manner with a maximum of two negative compounds for each orbital. This principle provides additional instructions on the location of electrons. Each orbital must have a maximum of two electrons, as we have said, but according to Hund’s rule it is necessary that each of the different orbital shells be filled with one electron before any of the orbitals can have two electrons. Therefore, it complements the need for atoms to be built in a staggered shape and always maintaining an angular position. In addition, the Moëller diagram also brings a new order to the orbitals and structures matter according to different levels. They all contribute new classification systems giving new points of view, just as it was discovered how lightning was produced.
Hund’s rule is a theory that has been widely used in quantum physics, obviously in addition to the chemical sector. For this reason, the exclusion principle formulated by Wolfgang Ernst Pauli comes to complement it. Basically, what it comes to say is that the same atom cannot have the same quantum numbers in the two electrons that form each of the orbitals. In fact, it just so happens that both Hund and Pauli made their theories in 1925, that is, the same year that allowed a breakthrough in this type of field. The theory of spin statistics later proved to be the main source of Pauli’s formulation. Without a doubt, Friedrich Hund ended up being one of the main actors that allowed enormous progress in the world of physics and chemistry, and that Currently many other scientists have been allowed to benefit.