I need the explanation of this para
Solution:
The atomic numbers of B and Al are 5 and 13 respectively with electronic configuration
[He] 2s22p1 and [Ne] 3s23p1.
B and Al have a noble gas inner shell whereas its valence shell contains electrons in ns and np-subshell.
The atomic numbers of Ga and In are 31 and 49 respectively with electronic configuration
[Ar] 3d104s24p1 and [Kr] 4d105s25p1.
Ga and In have a noble gas inner shell and its valence shell contains electrons in ns and np-subshell.
But their penultimate shell (n-1)d-subshell contains 10 electrons absent in B and Al.
Thallium(Tl) has a atomic number 81 and a configuration of [Xe] 4f14 5d106s26p1
which shows presence of electrons not only in penultimate (n-1)d-subshell (d10) but also in anti-penultimate (n-2) f-subshell (4f14)
Thus as we go higher in the period, d-subshell and f-subshell form the part of the electronic configuration.
The atomic numbers of B and Al are 5 and 13 respectively with electronic configuration
[He] 2s22p1 and [Ne] 3s23p1.
B and Al have a noble gas inner shell whereas its valence shell contains electrons in ns and np-subshell.
The atomic numbers of Ga and In are 31 and 49 respectively with electronic configuration
[Ar] 3d104s24p1 and [Kr] 4d105s25p1.
Ga and In have a noble gas inner shell and its valence shell contains electrons in ns and np-subshell.
But their penultimate shell (n-1)d-subshell contains 10 electrons absent in B and Al.
Thallium(Tl) has a atomic number 81 and a configuration of [Xe] 4f14 5d106s26p1
which shows presence of electrons not only in penultimate (n-1)d-subshell (d10) but also in anti-penultimate (n-2) f-subshell (4f14)
Thus as we go higher in the period, d-subshell and f-subshell form the part of the electronic configuration.