Dmitri Mendeleev (jan 1, 1869 – jan 1, 1869)

Description:

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Introduction and Basis:
After the failure of Newland's octaves, Dmitri Ivanovich Mendeleev, a Russian chemist, put forward a periodic table that was called the Mendeleev periodic table, which he published in 1869. He is widely credited with developing the modern periodic table of elements. He examined the relationship between the atomic masses of the element and their physical and chemical properties.
Mendeleev's periodic table was primarily based on the atomic weights of the elements. He believed that the atomic mass of an element was the most fundamental property in classifying the elements. He arranged the known elements in the increasing order of their atomic masses and their properties and thus created the first periodic table containing 63 elements. The horizontal rows in the periodic table are called periods (a total of 7), and the vertical columns are called groups.

Examples:
For example, since he grouped elements with similar properties together into families or groups, the elements of sodium (Na) and lithium (Li) are alkali metals thus sharing similar properties.

Limitations and Comparisons:
In Mendeleev's periodic table, there were some limitations. Firstly, no fixed position could be given to hydrogen in the table as it resembled alkali metals as well as halogens. Also, at certain places, an element of higher atomic mass was placed before an element of lower mass.

In comparison with Newland's table, Mendeleev's was more effective as he kept some vacant/blank spaces for elements that were yet to be discovered.
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