Effective Atomic Number

A blue colour complex is obtained in the analysis of Fe^(+3) having formula Fe_(4)[Fe(CN)_(6)]_(3) Let a= oxidation number of Iron in the corrdination sphere b= no. of secondary valencies of central iron ion. c=Effective atomic number of Iron in the coordination sphere. Then find the value of (c+a-2b)

180 electron rule: Valence shell of a transition metal consists of nine valence orbitals of (n-1) d, ns and np sub-shells, which can accommodate 18 electrons. When a metal complex has 18 valence electrons, it is said to have achieved the same electronic cofiguration as the noble gas at the end of the period. The rule and its exception are similar to the application of the octet rule of main group elements. The rule is not helpful for complexes of the s-block metals, the lanthanides or actinides. Effective atomic number is the total number of electrons possesed by the central possesed by the central metal atom/ion including the electrons contributed by the ligands. It is obvious that if a central transition metal atom/ion achieves 18 electrons in its valence shell, it attains the nearest noble gas cofiguration, which is known as effective atomic numbr (EAN) rule. [Atomic number :Cr=24, Fe=26, Cu=29, Ni=28, Rh=45] The effective atomic number of Rhodium in is :

Analysis of body centered cubic unit cell|Effective number of atoms|Coordination number|Packing fraction

Analysis of face centered cubic unit cell|Effective number of atoms|Coordination number|Packing fraction

The effective atomic is shown by

In Silicon crystal silicon atoms constitutes fcc where four out of 8 tetrahedral holes are also occupied by SI atom.Calculate the total number of effective atoms in a unit cell