Periodic Table of Elements in Brief

Periodic Table of Elements is a tabular method of displaying chemical elements, invented by the famous Russian chemist Dmitri Mendeleyev in 1869. He realized that many properties of chemical elements are periodic functions of their atomic numbers – came to be known as the periodic law – and by ordering the different chemical elements in rows and columns, he intended to emphasize the periodic properties of elements in an easy comprehendible format. Many new elements have been discovered since Mendeleyev had designed his periodic table, but they all were incorporated into the table by following the same rules as was followed by Mendeleyev himself in shaping his periodic table.

In a periodic table, the rows represent periods, and columns represent groups. Group elements have similar chemical properties as the number of valence electrons in them is the same. On the other hand, as per the quantum mechanical theories governing electron configuration inside atoms, each period in the table corresponds to the filling of a quantum shell of electrons. This is the reason why there are progressively longer periods exists towards the bottom half of the periodic table, including lanthanides and actinides. Also, elements in certain periods show clearly visible trends in atomic radius, electron affinity, ionization energy, and electro negativity, to an extent that it sometimes outweighs the significance of group classifications (for e.g. d-block and f-block).

At present, there are 117 elements in the periodic table, with 118 being the last element (117 is yet to be synthesized). 92 of them are naturally found on earth, while the rest are synthetically made. However, Neptunium and Plutonium, even though listed alongside synthetic elements, later they have been found to exist in small traces on the earth’s crust.

Since periodic table of elements are printed by many publishers these days, it could differ a bit here and there as some displays the element symbol and atomic number with each element name, while some may also include other information like element’s atomic mass, electro negativity, valence number, abbreviated electron configuration etc as well. Otherwise, they are all the same, elements ordered according to their chemical properties.

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