Question

write a note on geneis of periodic classification citing each method adopted till formulation of modern periodic table. for 5 marks​

Answer 1

Answer:

A periodic table is an arrangement of chemical elements.They are classified on the basis of their atomic numbers , electronic configuration and properties.Elements discovered till now are arranged in the table from 1 to 118 atomic numbers.The elements are spread out in 18 columns and 7 rows.The elements include metals , non-metals ,metalloids, transition metals , inner transition metals where most of them are solid in nature except few which are gases and only one is liquid( mercury ).

Some of the periodic tables also existed prior to this modern periodic table such as table by Dmitri Mendeleev known as Mendeleev table. It was made on the basis of the properties of the elements known then.It also predicted the properties of some elements not discovered at that time and they were proved to be correct after the discovery of these elements.

In 1817 , another scientist attempted classification of elements in pairs of three elements which had similar atomic weights. This was called a law of triads.

Many more classification were also done such as Telluric screw ( helix)  , Newland's law of octaves , Lothar-Meyer arrangement but these were not much successful as the mendeleev and modern periodic table were.

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