Isobars are places that have the same average atmospheric pressure.
The Greek word isobarḗs , which refers to that “of equal weight” , came into French as isobare . It arrived in our language as isobaro or isóbaro , as accepted by the Royal Spanish Academy ( RAE ).
Regarding the etymology of the word isobaro , its origin takes us back to the Greek language, where we find the components isos and baros , which mean "equal" and " weights ", respectively. This refers us once again to the equality of weights that exists between the pairs of nuclear species that can be classified in this way. We can observe the first of these components in the other related terms.
The term in meteorology
The concept is used in the field of meteorology to name two or more places that have the same average atmospheric pressure . The line that, on a weather map, allows joining those places that have identical atmospheric pressure at a specific time is also called isobar.
To understand what isobars are, in this way, we must first focus on the notion of atmospheric pressure . This is the name given to the pressure exerted by the atmosphere on all the bodies found in it. The atmospheric pressure considered normal is 1013 mbar or 760 mm Hg at sea level.
In chemistry, atoms that have the same mass number but different atomic numbers are called isobars.
Isobars in chemistry
In the field of chemistry , on the other hand, isobars are those atoms that have the same mass number, although different atomic numbers . This means that they are atoms of various chemical elements, with different chemical properties. In addition, they come from different chemical elements.
The mass number or mass number reflects the sum of the number of protons and neutrons in the nucleus of the atom. The atomic number , meanwhile, refers specifically to the number of protons.
It is necessary to note that the net number of protons and neutrons found in each nucleus does not vary. In other words, the origin of an isobarous species occurs when two atomic nuclei exhibit the same net number of protons and neutrons for their respective species.
Despite this, the number of protons and neutrons that are part of said total is different. To be able to visualize this graphically, it is possible to take a look at the mass number, which in the periodic table is found in the upper left corner of the symbols of the chemical elements: in two isobars, this value is identical.
Similar notions
It is important not to confuse isobars with isotopes . Isotopes are atoms with the same atomic number and different mass number (unlike isobars): that is why they have the same chemical properties and belong to the same chemical element. Isotones , likewise, have different atomic numbers and different mass numbers.
Another species with which isobars have some similarities with respect to their nuclei is that of isotones , which are briefly mentioned in a previous paragraph. Among the coincidences they have is the number of neutrons, which is the same; However, the atomic number and mass are different, something that can be seen in several pairs of elements.
We must also take into account the word nuclide , which is used to name the different possible groups of nucleons, the structures that are made up of protons and neutrons. Nuclides, therefore, can be differentiated by the number of protons or neutrons, or also by the amount of energy seen in the structure of their conglomeration.
The use of the term isobars to denote species considered nuclides with the same number of nucleons (that is, having the same mass number) was proposed by a chemist from Great Britain named Alfred Walter Stewart in the 1910s.