The periodic table and what exactly are the spdf orbitals? It takes a bit of getting used to. Having said that, it is the most amazing set up of any spreadsheet or chart that you will ever come across.
S block elements
s sub shell has only 1 orbital which can accommodate only 2 electrons, therefore, there are only two groups of s block elements.
Elements of and group 1(hydrogen and alkali metals) and group 2 (alkaline earth metals) and helium comprises s block element.
Hydrogen has only one electron and this enters 1s orbital. The rest of the elements i.e. Li, Na, K, Rb, Cs and Fr receive the last electron in 2s, 3s, 4s, 5s,6s and 7s orbitals. There are 14 s-block elements in the periodic table.
General electronic configuration of s-block elements: ns1-2 where n=2-7

Helium belongs to s – block but its positioning with in the p block along with other group 18 elements is justified because it has a completely filled valence shell and thus exhibits properties characteristic of other noble gases.
P block elements
Elements in which the last electrons enter any one of the three p orbitals of their respective outermost shell are called p block elements.
A p sub shell has three degenerate p orbitals ,each one of which can accommodate 2 electrons.
There are 6 groups of p block elements. These are 13,14,15,16, 17and 18.
The atoms of the elements belonging to these groups receive the last electron in 2p, 3p, 4p, 5p and 6p orbitals.
Their outer shell electronic configuration vary from ns1 np6 to ns2 np6 as we move from group 13 outward up to group 18.
Elements of group 13, 14 ,15 ,16 ,17 ,18 in which p orbitals are being progressively filled in are called p block elements. There are 36 p-block elements in the periodic table.
Group 18 are called noble gases, except helium all the elements have closed shell ns2 np6 electronic configuration in the outermost shell. All the energy levels which are occupied are completely filled and this stable arrangement of electrons cannot be easily altered by addition or removal of electrons. As a result , these elements are highly stable and hence exhibit very low chemical reactivity.
The elements of s and p block are called representative or main group elements.

d-Block elements
Elements in which the last electron enters any one of the five d orbitals of their respective penultimate shells are called d- block element.
Since a d sub shell has 5 d-orbitals, each one of which can accommodate 2 electrons ,therefore, in all there are 10 vertical columns comprising 10 groups of d- block elements namely 3, 4 ,5 ,6 ,7 ,8 ,9 ,10 ,11 and 12.
The atoms of the elements belonging to these groups usually have 1 or 2 electrons in the s orbital of the outermost shell i.e. ns orbital while the electrons are being progressively filled in, one at a time in the d orbital of the respective penultimate shell i.e. (n-1) d orbital.Thus
General outer shell electronic configuration of d block elements: (n-1)d1-10 ns1-2
where n=4-7.
The properties of these elements are midway between those of s- block and p- block elements ,they are also called transition elements .All these elements are further divided into four series called 1st ,2nd ,3rd and 4th transition series.
The first transition series forms a part of the fourth period of the long form of periodic table.It contains 10 elements from scandium(Z=21) to zinc( Z=30) in which 3d orbitals are being progressively filled in.
The second transition series which forms a part of the 5th period also contains 10 elements from Ytterium(Z= 39) to cadmium(Z=48) in which the 4d orbitals are being progressively filled in.
The third transition series which form a part of the sixth period also contains 10 elements i.e. lanthanum(Z=57) and from hafnium(Z=72) to mercury(Z=80) in which the 5d orbitals are the progressively filled in.
The fourth transition series which forms a part of 7th period also contains 10 elements i.e. actinium (Z=89) and element from rutherfordium(Z=104) to Copernicium( Z=112) .In all these elements 6d orbitals are being successively filled in.
The elements of group 3 ,4 ,5 ,6 ,7 ,8 ,9 ,10 ,11 and 12 belonging to 4th 5th 6th and 7th period in which the last electron enters the d orbital of their respective penultimate shells are called d Block Elements. There are 40 d block elements in the periodic table.

f-Block elements
The elements in which the last electron enters any one of the 7 f-orbitals of their respective ante -penultimate shell are called f block elements.

In all these element the s orbital of last shell is completely filled ,the d orbital of the penultimate(n-shell invariably contains 0 or one electron but the f orbital of the ante-penultimate (n-2) gets progressively filled in.
General outer shell electronic configuration of f block elements: (n-2) f 0-14 (n-1) d0-1 ns2
There are two series of f block elements each containing 14 elements. These are placed at the bottom of the periodic table.

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