The arrangement helps in easy memorizing of the elements in periodic table with the easy knowledge of oxidation state and properties of group of elements.
Step-by-step explanation:
The groups consists of elements having same valence state and similar properties while the elements in periods are arranged in increasing atomic number.
So the period helps in remembering the atomic number and mass number of every element from their period number.
While the group number helps in finding the oxidation state, valence electrons and chemical properties of the elements present in that group.
Also it is easier to classify metals and non-metals and also semi-metals with the grouping of their group numbers.