Question
Sat July 07, 2012 By:
 

describe in detail the ways electron of an element arrange themselves in the sub shells(s,p,d.f).also state the reason with respect to the above,why do some elements have variable valency?

Expert Reply
Sat July 07, 2012
The order in which electrons fill orbitals about a nucleus is very systematic. It is not however in direct order from s orbital to f orbital at a level. In many cases orbitals at a higher energy level fill before all orbitals at a lower energy level have been completely filled.
 
A subshell is the set of states defined by a common azimuthal quantum number, l, within a shell. The values l = 0, 1, 2, 3 correspond to the spd, and f labels, respectively. The maximum number of electrons which can be placed in a subshell is given by 2(2l + 1). This gives two electrons in an s subshell, six electrons in a p subshell, ten electrons in a d subshell and fourteen electrons in an f subshell.
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