The decrease in the size of atoms or ions with increase in the atomic number among the lanthanides is known as
Lanthanoid contraction
f-f transition
Actionoid contraction
shielding effect

The decrease in stability of higher oxidation state in p-block with increasing atomic number is due to:

The decrease in stability of higher oxidation state in p-block with increasing atomic number is due to:

In a transition series, as the atomic number increases, paramagnetism

The order of increasing sizes of atomic radii among the elements O, S, Se and As is :

The gradual decrease in size (actionoid contraction) is from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction).

The size of the trivalent cations in the lanthanoid series decreases steadily as the atomic number increases. What is this known as ?

In the transition series, with an increase in atomic number, the atomic radius does not change very much. Why is it so?

The electropositive character of alkali metals decreases with an increase in atomic number. True or False

Assertion : 4d and 5d series elements have nearly same atomic radius. Reason : Lanthanoid contraction.

Give an explanation for each of the following observations: (i) The gradual decrease in size (actinoid con-traction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction). (ii) The greater number of oxidation states are exhibited by the members in the middle of a transition series. (iii) With the same d-orbital (d^4) , Cr^(2+) ion is a reducing agent but Mn^(3+) ion is an oxidising agent.