Question

What is a periodic table ? How many groups and periods does the modern periodic table have ?

Answer 1

Hint: The periodic table is significant because it is organised to provide a wealth of information about elements and their relationships in a single, easy-to-understand reference. The table can be used to guess the properties of elements that haven't been discovered yet. The contemporary periodic table is still frequently used in chemistry, nuclear physics, and other sciences because it provides a useful framework for evaluating chemical reactions.

Complete answer:
The periodic table is a table that presents chemical elements in order of increasing atomic number, allowing one to see trends in their properties. Dmitri Mendeleev, a Russian scientist, is credited with developing the periodic table (1869). The contemporary periodic table is based on Mendeleev's periodic chart, but with one major difference. The elements in Mendeleev's table were organised by increasing atomic weight rather than atomic number. His table, on the other hand, showed repeated trends or periodicity in the properties of the elements.
The periodic table's layout allows you to see correlations between elements at a glance and forecast properties of unfamiliar, recently found, or undiscovered elements.
Group: A group is a column in the periodic chart of chemical elements in chemistry. Chemical elements in a group have atoms with equal valence electron counts and valence vacancy counts. The groups are numbered one through eighteen.
Period: Periods are the horizontal rows of the periodic table. Each period represents the consecutive occupation of orbitals in an atom's valence shell, with the long periods representing the occupation of orbitals in a d subshell.
In the modern periodic table, there are eighteen vertical columns, known as groups, that are organised from left to right, and seven horizontal rows, known as periods.

Note:
In the present periodic chart, which is comparable to Mendeleev's periodic table, hydrogen has no set place. In the first period, hydrogen can be assigned to either group 1 or group 17 since its properties are comparable to those of both groups. Because isotopes are atoms of the same element with varying atomic masses, they should be arranged in the order of atomic mass in a different order. This, however, was not done. There is no proper place for lanthanoids and actinoids. Helium's placement is not justified: helium should be in group two with alkaline earth metals based on electrical configuration, but it has been placed in group eighteen with noble gases based on its qualities.