Why is 2d1 not possible?

Answer 1

A break down of 2d1:

2 = the quantum energy level or electron shell denoted as 'n'


d = the sub-shell of the energy level (known as a degenerate level)


1 = the number of electrons occupying the sub-shell.






Through extensive research by scientists, no known element has a d sub-shell in the second (n=2) energy level. In fact, the d sub-shell does not appear until the fourth period (fourth row).


The first d sub-shell is known to be in the third energy level (therefore the first energy level with this sub-shell is 3d, but not 2d).


Transition metals are the elements known to fill the d sub-shells. The first transition metal in the Periodic Table is scandium (Sc) with the electron configuration of [Ar]4s23d1.


The reasons for the formation of sub-shell of d is beyond my knowledge and the scope of basic chemistry.