In the long form of periodic table the total number of periods is
a) 5
b) 7
c) 8
d) 9
Answers
Answered by
9
Periodic table is a table for the convenience for the learning of different elements and their different properties. The periodic table which is being used in present is known as 'modern periodic table' or 'long form of periodic table".
Early chemisis, arranged the elements on the basis of their valency, metallic and non - metallic characters, but that method was discarded as elements showed 'variable valency and dual character'.
After this incident, Dobereiner, in 1815 , arranged the periodic table on the basis of the increasing order of their atomic weights, but this method was also discarded, as atomic weight of middle element wax found generally to be the average of the remaining two, but this didn't hold true for all elements.
In 1864, Newland redesigned the periodic table, but like Dobereiner he too arranged the elements in increasing order of their atomic weight and his method was also discarded because there was no space for undiscovered elements.
In 1869, a periodic table was given by a scientist named 'Mendeleeff', which was based on the mass number of the elements. It was much better than the other previous tables. And, it was based on the increasing order of the mass number of the elements. Although the table was based on increasing order of their atomic mass, at few places elements with less atomic number were placed before the elements with more atomic number. Later on, table given by Mendeleeff was rejected and this forced scientists to believe that the atomic mass can't be a perfect property for placings elements.
After few years[ in 1912 ], a scientist named 'Henry Moseley' designed a new periodic table but it was based on the increasing order for atomic number ( number of protons present in the element ), not on atomic mass.
This was divided into vertical and horizontal rows & columns.
There were 7 rows in the whole periodic table, and rows were named as Periods.
Hence,
Total number of periods in the long form periodic table is 7.
Option B is correct.
Early chemisis, arranged the elements on the basis of their valency, metallic and non - metallic characters, but that method was discarded as elements showed 'variable valency and dual character'.
After this incident, Dobereiner, in 1815 , arranged the periodic table on the basis of the increasing order of their atomic weights, but this method was also discarded, as atomic weight of middle element wax found generally to be the average of the remaining two, but this didn't hold true for all elements.
In 1864, Newland redesigned the periodic table, but like Dobereiner he too arranged the elements in increasing order of their atomic weight and his method was also discarded because there was no space for undiscovered elements.
In 1869, a periodic table was given by a scientist named 'Mendeleeff', which was based on the mass number of the elements. It was much better than the other previous tables. And, it was based on the increasing order of the mass number of the elements. Although the table was based on increasing order of their atomic mass, at few places elements with less atomic number were placed before the elements with more atomic number. Later on, table given by Mendeleeff was rejected and this forced scientists to believe that the atomic mass can't be a perfect property for placings elements.
After few years[ in 1912 ], a scientist named 'Henry Moseley' designed a new periodic table but it was based on the increasing order for atomic number ( number of protons present in the element ), not on atomic mass.
This was divided into vertical and horizontal rows & columns.
There were 7 rows in the whole periodic table, and rows were named as Periods.
Hence,
Total number of periods in the long form periodic table is 7.
Option B is correct.
Anonymous:
Yah 7 is correct that is option b
Such a good answer...☺☺
:-)
Answered by
6
The total no. Of period are 7
Similar questions