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Transition Metals: Class 12 Inorganic Chemistry Notes

NEB Class 12 Chemistry Unit 6: Transition Metals Complete Notes. Transition Metals Complete Notes With Question Answer, FAQs, MCQs, Important Question

Unit 6. Transition metals

Unit 6 Transition Metals
6.1 Explain characteristics of transition metals.
6.2 Explain oxidation states of transition metals.
6.3 Describe complex ions and metal complexes.
6.4 Show shapes of complex ions.
6.5 Describe d-orbitals in complex ions (simple explanation by crystal field theory) for octahedral complex.
6.6 Explain reasons for the colour of transition metal compounds.
6.7 Explain catalytic properties of transition metals.

Transition Metals Class 12 NEB Chemistry Notes


Three series of elements formed by filling the 3d, 4d, and 5d shells of electrons are called d-block elements.

The electronic configuration of d-block elements are generally represented
by (n-1)d^1-10 ns^1-2 . Where (n-1) is penultimate shell.

In s-block and p-block element, the outermost orbital is filled. But in the d-block element electrons are added to the penultimate shell.

They are often called ‘transition elements’ because their position in the periodic table is between the s-block element( which formed ionic compound ) and the p-block element( which are largely covalent ).

Transition series

  • There are three complete rows of ten elements and one incomplete row in d-block of periodic table.
  • These rows are called first, second, third, and fourth transition series which involves filling of 3d, 4d, 5d, and 6d orbitals respectively.
  • These series are also called transition series.
  1. First transition series: It contains ten elements from Scandium(At. No. 21) to Zinc (At. No. 30). They have incomplete 3d-orbitals.
  2. Second transition series: It contains ten elements from Yttrium (At. No. 39) to Cadmium(At. No. 48). They have incomplete 4d-orbitals.
  3. Third transition series: It contains ten elements with incomplete 5d�-orbitals and constitute elements Lanthanum (At. No. 57) and from Hafnium (At. No. 72) to Mercury(At. No. 80).
  4. Fourth transition series: It has incompletely filled f-group elements. This consist of Lanthanide and actinides.

Transition Metals Class 12 NEB Chemistry Notes Pdf

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