What are actinoids ? Write the name of all the actinoids.

What are lanthanoids? Write the name of the lanthanoids.

Write the IUPAC name of

Write the names of all the VIIA group elements.

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

Compare the chemistry of actinoids with that of the lanthanoids with special reference to:

Which is the last element in the series of the actinoids? Write the electronic configuration of this element. Comment on the possible oxidation state of this element.

(i)with reference to structural variability and chemical reactivity write the differences between lanthanoids and actinoids (ii) Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state

(a) When a chromite ore (A) is fused with an aqueous solution of sodium carbonate in free excess of air, a yellow solution of compound (B) is obtained. This solution is filtered and acidified with sulphuric acid to form compound (C). Compound (C) on treatment with solution of KCl gives orange crystals of compound (D). Write the chemical formulae of compounds A to D. (b) Describe the cause of the following variations with respect to lanthanoids and actinoids: (i) Greater range of oxidation states of actinoids as compared to lanthanoids. (ii) Greater actinoid contraction as compared to lanthanoid contraction. (iii) Lower ionisation enthalpy of early actinoids as compared to the early lanthanoids.

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.

How would 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 seconds (4d) series. (ii) There is a greater range of oxidation states among the actinoids than among the lanthanoids.