Question

How many groups and periods present in Mendeleev’s periodic table?

Answer 1

Hint: To find groups and periods present in the Mendeleev periodic table, first we will discuss the postulates of Mendeleev's periodic table and we will arrange elements according to their increasing atomic masses. The tabular form of Mendeleev is known in Mendeleev's periodic table. Horizontal rows are called periods and the vertical columns are called groups.

Complete step by step answer:
While developing the periodic table, there were a few instances where Mendeleev had to place an element with a slightly greater atomic mass before an element with a slightly lower atomic mass.
Further, Mendeleev's left some gaps in his periodic table. Instead of looking upon these gaps as defects, Mendeleev boldly predicted the existence of some elements that had not been discovered at that time. Mendeleev named them by prefixing an Eka(one) to the name of the preceding element in the same group. For example scandium, gallium and germanium discovered later, have similar properties with Eka-boron, Eka-aluminium and, Eka-silicon , respectively. Noble gases like helium, neon, and argon have been mentioned in many contexts before this.
Limitations of Mendeleev's periodic table: Electronic configuration of hydrogen resembles that of alkali metals because when hydrogen and alkali metals combine with halogens, Oxygen and sulphur they give the compound of similar formula. Hydrogen could not be given the fixed position in the periodic table and this was the first limitation of Mendeleev's periodic table.

After discussing the Mendeleev’s periodic table, we came to know that there are seven periods and eight groups in Mendeleev’s periodic table.

Note:
Inert gases were discovered very late because they were inert and present in extremely low concentrations in our atmosphere and when these gases were discovered, they are placed in a new group without disturbing the existing order.