Solution

According to the type of subshell being filled, the elements can be divided into the given categories- the representative elements, the noble gases, the transition elements, the lanthanides and theactinides. The representative elements (also called main group elements) are the elements in I A through VII A, all of which have incompletely filled s or p-subshells of the highest principal quantum number. The noble gas (group VIII A) have a completely filled P-subshell, except for helium, which have completely filleds-subshell. The transition metals are the elements in groups I B and II B through VII B, which have incompletely filled d-subshells or readily produce cations with incompletely filled d-subshells.