" The metallic radii of "4d" and "5d" series of transition metals are nearly the same.Why? "

How would you account for the following ? (i) Among lanthanoids, Ln (III) compounds are predominant. However, occasionally in solutions or in solid compounds, +2 and +4 ions are also obtained. (ii) The E^@(M^(2+)| M) for copper is positive (0.34V). Copper is the only metal in the first series of transition elements showing this behaviour. (iii) The metallic radii of the third (5d) series of transition metals are nearly the same as those of the corresponding members of the second series.

How will you account for the following ? (i) The metallic radii of the third (5d) series of transition metals are virtually the same as those of the corresponding group members of the second (4d) series. (ii) Lanthanoids form primarily +3 ions while actinoids usually have higher oxidation states in their compounds . Among the lanthanoids, Ln(III) compounds are predominant. However, occasionally in solution or in solid state +2 and +4 ions are obtained. Explain.

The atomic radii of the metals of the third (5d) series of transitions elements are virtually the same as those of the corresponding members of the second (4d) series. Explain.

How would you account for the following? (i) The atomic radii of the metals of the third (5d) series of transition elements are virtually the same as those of the corresponding member of the second (4d) serie (ii) Because oxygen and fluorine are highly electronegative elements and small in size.