The Total solution for NCERT class 6-12
Give special emphasis on the following points(i) electronicconfigurations(ii) oxidation states(iii) ionisation enthalpiesand(iv) atomic sizes.
(i) Electronicconfigurations : In 1st transitionseries, 3d-orbitals are progressively filled whereas in 2nd transitionseries, 4d-orbitals are progressively filled and in 3rd transitionseries, 5d-orbitals are progressively filled.
(ii) Oxidationsstates : Elements show variable oxidation statesin both the series. The highest oxidation state is equal to total number ofelectrons in ‘s’ as well as ‘d’ orbitals. The number of oxidation states shownare less in 5d transition series than 4d series. In 3d series +2 and +3oxidation states are common and they form stable complexes in these oxidationstates. In other series OsO4 and PtF6 areformed which are quite stable in higher oxidation state.
(iii) Ionisationenthalpies : The ionisation enthalpies in each seriesgenerally increases gradually from left to right. The ionisation enthalpy of 5dseries do not differ appreciably due to lanthanoid contraction.
(iv) Atomic sizes : The atomic sizes of 4d and 5d-series do not differappreciably due to lanthanoid contraction. The atomic radii of second and thirdseries are larger than 3d series.