The long form of the periodic table is better than Mendeleev's periodic table because it classifies the elements on the basis of electronic configurations of their atoms.
The characteristics of this table are
(i) The table consists of 9 vertical columns, called the groups and 7 horizontal rows, called the periods.
(ii) The groups are marked 0 to VIII out of which group I to VII are subdivided into subgroups A and B
(iii) The group IA elements (Li, Na, K, Rb, Cs and Fr) are known as alkali metals and the group IIA elements (Be, Mg, Ca, Sr, Ba and Ra) are known as alkaline earth metals. Elements in group VIII A (F, Cl, Br, I and At) are called halogens and elements in group VIII (He, Ne, Ar, Kr, Xe and Rn) are called noble gases or rare gases.
(iv) The group VIII has there similar elements placed together in one place. These are called transition triads, e.g., Fe, Co and Ni, Ru, Rh and Pd; Os, lr and Pt etc.
(v) In the 6th and 7th period, 14 elements present called as lanthanides and actinides respectively.
(vi) Based on their electronic configuration, elements have been grouped into s-, p-, d- and f-blocks. This has helped us to understand their properties more easily.
(vii) There is gradual change in properties seen from one end to the other.
