The middle layer of the periodic table is filled with d block elements. The inner d orbits of group 3 to group 13 are filled progressively. On the other hand, f block elements are found outside at the bottom of the periodic table. In these elements, 5f and 4f orbitals are filled progressively. Three series of transition elements are recognized by the filling of 3d, 4d, 5d orbitals. They have high boiling and melting point. The metallic properties exhibited by the transition elements are
- Electrical conductivity
- Thermal conductivity
- High tensile strength
- Metallic character
The elements of the f block of the periodic table are two series of inner transition elements, actinoids, and lanthanoids. Due to the successive filling of the inner orbitals i.e 4f, the atomic and ionic sizes of these metals along the series gradually decreases. Lanthanoids are soft white metals and easily react with water. Their principle oxidation state is +3. +2 and +4 are also exhibited occasionally. Actinoid elements are radioactive and their chemistry is complicated. Some applications of d- and f-block elements are in the organic syntheses, catalysts, etc.
Few Important Questions
- Write the electronic configuration for the following elements
Mn2+, Cu+, Pm3+, Th4+
- Define interstitial compounds. Explain why these compounds are known as transition metals.
- What is disproportionation? Give an example of a disproportionation reaction occurring in an aqueous solution.
- Using Hund’s rule do the following:
Derive electronic configuration of Ce3+ ion, find the magnetic moment on the using the ‘spin-only’ formula
- What is meant by lanthanoid contraction?
- List the various oxidation states exhibited by the lanthanoids.
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