Question

Modern periodic table also known as long form of periodic table has the atomic number of elements as the basis of classification .It is better than mendeleev’s periodic table in many respects because it had regarded atomic masses of element as the basis of classification which is not correct .Actually mass of an element is concentrated mainly in the nucleus of the atom and has very little to do with the properties in particular .Electrons involved in these and are linked with atomic numbers of the element.

How many groups and periods are present in the long form of periodic table?

Answer 1

1. In the modern periodic table, there are 18 vertical columns. The elements present in these columns have the same valence shell electronic configuration and same valency. These vertical columns are known as groups.
2. In the periodic table, there are 7 horizontal rows that contain elements having the same number of electron shells, these are termed as periods.
3. There is a total of $18$groups and $7$periods in the periodic table.