What Does periodic table Mean
It is known as the periodic table of the elements , periodic system or simply as the periodic table , a scheme designed to organize and segment each chemical element, according to the properties and particularities that it possesses.
It is a fundamental tool for the study of chemistry as it allows us to know the similarities between different elements and understand what can result from the different unions between them.
Development process of the periodic system
As noted when investigating the periodic table, the history of this structure is related to the discovery of the different chemical elements and the need to order them in some way.
Since the beginning of science, we have tried to understand the why and how of matter and the elements that make up our system. Thanks to the different experiences of scientists, it has been possible to further decompose matter to analyze it inch by inch, finally finding out that it is much more complex than what it seems at first glance.
From the 19th century on, scientists had the need to establish an order in the elements discovered. The way in which they decided to do it, was starting from their atomic masses and grouping those that were similar; However, this task was not so simple since it was difficult to reflect in an ordered table the similarities and differences between them.
The chemist Döbereiner was the one who in 1817 presented a report that reflected the relationship that existed between the mass and the properties of the different elements. Thus he formed groups of similar elements , such as triads, such as the one that forms chlorine, bromine and iodine, where the mass of one of them is located in the middle of the other two. Based on this research, in 1850, around 20 triads were assembled .
Later, Chancourtois and Newlands discovered the Law of Octaves, which allowed improving not only the distribution of the elements in the table, but also the relationships reflected in it. This Law observes that the chemical properties are repeated successively every eight elements. However, some elements broke with it, so it was not enough to establish a clear coherence in the table.
When in 1869 Meyer verified that the atomic volume of the elements presented a certain periodicity; It was known that certain elements had a similar volume to those elements that resemble them in composition.
Finally, in 1869 Mendeleev presented the first version of the periodic table . It was made up of a column with 63 elements, grouped according to their common properties, and several blank spaces. The Russian chemist assumed that some were missing that had not been discovered, those corresponding to the atomic masses that were not yet known and that allowed the table to have an absolute numerical regularity. Although at the time, his theory was not accepted, as it seemed inaccurate, years later when discovering the missing elements , it was proven that Mendeleev was right.
Later, Mendeleev added the formulas for the oxides and hydrides in each section. At the end of the 19th century, the periodic table began to include the zero group (with the so-called noble gases), called that way because of the absence of chemical activity (zero valence).
Finally, it is necessary to recognize the importance of John Dalton ( 1766 - 1844 ) in the development of the concept of chemical atomism, by assuming about the possible combinations of the atoms of substances. Dalton chose the mass of a hydrogen atom as the referential unit and created a structure based on relative atomic masses.