history of the periodic table,how it is organise?

Question

i.e what are periods,what are group?atomic number;electronic structures

Answer 1

Dmitri Mendeleev, also spelt Dmitry Mendeleyev, middle name (patronymic) Ivanovich, a Siberian-born Russian chemist, was the first scientist to make a periodic table much like the one we use today. Mendeleev arranged the elements in a table ordered by atomic mass. It is sometimes said that he played "chemical solitaire" on long train rides using cards with various facts of known elements.[6]On March 6, 1869, a formal presentation was made to the Russian Chemical Society, entitled The Dependence Between the Properties of the Atomic Weights of the Elements. His table was published in an obscure Russian journal but quickly republished in a German journal, Zeitschrift für Chemie, in 1869. It stated

The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.
Elements which are similar as regards to their chemical properties have atomic weights which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs).
The arrangement of the elements, or of groups of elements in the order of their atomic weights, corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, Ba, C, N, O, and Sn.
The elements which are the most widely diffused have small atomic weights.
The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.
We must expect the discovery of many yet unknown elements–for example, elements analogous to aluminium and silicon–whose atomic weight would be between 65 and 75.
The atomic weight of an element may sometimes be amended by a knowledge of those of its contiguous elements. Thus the atomic weight of tellurium must lie between 123 and 126, and cannot be 128.
Certain characteristic properties of elements can be foretold from their atomic weights.
In 1914, Henry Moseley found a relationship between an element's X-ray wavelength and its atomic number and therefore resequenced the table by electronic charge rather than atomic weight. Before this discovery, atomic numbers were just sequential numbers based on an element's atomic weight. Moseley's discovery showed that atomic numbers had an experimentally measurable basis.

Moseley's research also showed that there were gaps in his table at atomic numbers 43 and 61 which are now known to be radioactive and not naturally occurring. Following in the footsteps of Dmitri Mendeleyev, Henry Moseley also predicted new elements.

During his Manhattan Project research in 1944, Glenn T. Seaborg experienced unexpected difficulty isolating Americium (95) and Curium (96). He began wondering if these elements more properly belonged to a different series which would explain why the expected chemical properties of the new elements were different. In 1945, he went against the advice of colleagues and proposed a significant change to Mendelev's table: the actinide series.

Seaborg's actinide concept of heavy element electronic structure, predicting that the actinides form a transition series analogous to the rare earth series of lanthanide elements, is now well accepted in the scientific community and included in all standard configurations of the periodic table. The actinide series are the second row of the f-block (5f series) and comprise the elements from Actinium to Lawrencium. Seaborg's subsequent elaborations of the actinide concept theorized a series of superheavy elements in a transactinide series comprising elements 104 through 121 and a superactinide series inclusive of elements 122 through 153.

Answer 2

You want to look up:
Dobereiner (and his triads)
Newlands (and his Octaves)
Mendeleev.

Then you will begin to understand about the horizontal rows called periods, the vertical columns called groups, the fact that from left to right atomic number goes up by one each time, and the relevance nowadays to the electronic structures of the elements.