Illustration 1:
Through copper, silver and fold have completely filled sets of d-orbitals yet they are considered as transition metals. Why?
Solution:These metals in their common oxidation states have incompletely filled d-orbitals e.g. Cu2+ has 3d9 and Au3+ has 5d8 configuration.
Illustration 2:Zinc, cadmium and mercury are generally not considered as transition metals. Give reasons.
Solution:These elements in their most common oxidation state of +2 have completely filled d-orbitals.
ELECTRONIC CONFIGURATION
The general electronic configuration is (n – 1)1-10 ns1-2 where n is the outermost shell. The number of electrons in their outermost subshell remains two while their penultimate shell of electrons expands from 8 to 18 electrons.
Electronic configuration of 3d series
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3d14s2 |
3d24s2 |
3d34s2 |
3d54s1 |
3d54s2 |
3d64s2 |
3d74s2 |
3d84s2 |
3d104s1 |
3d104s2 |
Anamolous configuration of Cu and Cr
Copper and chromium have a single electron in 4s-orbital. This is due to the gain of additional stability by the atom having either half-filled (5 electrons) or completely filled (10 electrons) d-shell.
Illustration 3: In what way is the electronic configuration of transition elements different form that of the non-transition elements?
Solution:Transition elements contain incompletely filled d-subshell i.e. their electronic configuration is (n – 1)d1-10ns0-2 whereas non-transition elements have no d-subshell or their subshell is completely filled and have ns1-2np1-2 in their outermost shell. |
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