How did the periodic table develop?
Since a very long time, elements such as gold, silver, tin, copper, lead and mercury have been known. But the concept of elements have largely be changed since then. Many scientists did research and new scientific discoveries were found. The progress of science never ends.
In 1789, French chemist Antoine Laurent Lavoisier discovered that an element is a fundamental substance that could not be broken down by any chemical means. He made a list of 33 elements but only classified elements as metals and non-metals,
In 1817, German chemist Johann Dobereiner started to attempt a classification of the elements. In 1829, he proposed that elements formed triads (groups of three) with related propreties. In all of the triads, the atomic mass of the second element was very close to the average of the atomic weights of the first and third elements. This was called the « Law of Triads ».
Mendeleev The Russian chemist Dmitri Mendeleev was the first scientist that produced a periodic table based on atomic weights and arranged ‘periodically’. He succeeded in arranging all known elements into one table. Elements were arranged in a table ordered by atomic mass, corresponding to relative molar mass. Elements with similar properties appeared under each other. Gaps were left for elements that needed to be discovered elements Mendeleev also worked out the “periodic law,” which was published in 1869 under the name « On the Relationship of the Properties of the Elements to their Atomic Weights ». The table is a visual representation of the periodic law which states that certain properties of elements repeat periodically when arranged by atomic number. The table arranges elements into vertical columns (groups) and horizontal rows (periods). In 1906, Mendeleev was awarded the Nobel Prize for his work. Through time, Mendeleev's periodic table has undergone...