Question

write the Inner Transition (f-block) Elements: Lanthanoids and Actinoids ​

Answer 1

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Elements whose f orbitals get filled up by electrons, are called f block elements. These elements are placed separately at the bottom of the periodic table. They are a subset of 6th and 7th periods.

Since f orbital lies much inside the d orbital, in relation to the transition metals the f block elements are called inner transition elements. These elements have 1 to 14 electrons in their f orbital, 0 or 1 in the penultimate energy level and 2 electrons in the outermost orbital. The lanthanoids are characterized by gradual filling up of 4f and actinides by the 5 f orbitals. There are 14 elements filling the f orbital in each series. The relative energies of the nd and (n-1)f orbitalsare very similar and are sensitive to electronic configurations.