Dmitri Mendeleev: The Development of the Periodic Table

Development of the Periodic Table

Introduction:

The Periodic Table of Elements is a table that arranges all known chemical elements by order of their atomic numbers. During the 1600s, vast amounts of knowledge about the properties of elements and their compounds were discovered and by 1869 63 elements had been discovered. As more and more elements were discovered, scientists began to recognise similarities between their properties and began to devise means of classification. Thus the periodic table of elements was created. The current periodic table contains 117 elements, however more may yet be discovered. The elements in the periodic table are classified in groups, periods and blocks. Groups refer to elements with similar properties and are the vertical columns of the table. The periods are the horizontal rows and illustrate the number of valence electrons each element has (how many electrons are in the outer shell of the element). The position an element is in on the table allows a scientist to easily judge its properties, its reactivity and its similarities to other elements.

Dmitri Mendeleev’s Periodic Table:

Dmitri Mendeleev, a Russian scientist, is said to be the father of the periodic table. In 1947 Mendeleev, while working on a textbook, began to organise the 63 elements that were known at the time in groups that displayed similar properties. Mendeleev found it difficult to classify certain alkali metals and metals, and while trying to find a way to classify them he began to notice that the properties and atomic weights of halogens and alkali metals shared similar patterns. He then began to investigate extensions of these patterns within the other elements. Mendeleev created a card for each of the known elements that sh...

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...the first version of the atomic theory, which then later allowed John Dalton to expand on the atomic theory to create a method of discerning atomic weight, was crucial in the development in the table. It was through finding the atomic weight of elements as well as classifying their properties that allowed Mendeleev to create his periodic table and discern possible new elements.

The work of JJ Thompson and James Chadwick was also important in creating the ‘finalised’ version of the periodic table. The discovery of the electron and then later the proton and neutron not only allowed for scientists to start trying to create a detailed model of the atom but also allowed for Henry Moseley to notice the patterns of protons between elements and thus create a more accurate rendition of Mendeleev’s table by ordering the elements by atomic number rather than atomic weight.