Question

if the electron configuration of an element is 1s22s22p63s23p64s23d104p2 what is the atomic no. of the element which is just below the above element in the periodic table

Answer 1

the element is galium....
the element above it is aluminium

Answer 2

"Germanium " is the element with the electron configuration [tex] 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{2} 3d^{10} 4p^{2} [/tex]

------------------------------------------------------------------------------------------------------------------

The atomic no. of the element which is just below the above element  i.e Germanium in the periodic table is 31 , the element is Gallium .(Gallium - electron configuration - $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{2} 3d^{10} 4p^{1}$)

By counting the number of electron by electronic configuration you can know the atomic number of that element and after this if you the elements by series in increasing order of atomic number then you can find with out taking help of periodic table . 
----------------------------------------------------------------------------------------------------------------
Best of luck ;)
ROYALJATT