Question

Give definition of Actinide series

Answer 1

Elements that lie in the f-block right after the Actinium are refered to as Actinides.

The differentiating electron of Actinides from Ac to Lw enters into pre-penultimate 5f-orbital. Because of this shielding effect remains very poor even if nuclear charge steadily increase. Consequently atomic radii of Actinides consistently decrease. This is called Actinide Contraction.

Answer 2

It is a series of heavy radioactive metallic elements of increasing atomic number considered to be analogous to the lanthanide series and to begin with actinium (89) or thorium (90) and end with element of atomic number (103).-compare actinide series.