D And F Block Elements Class 12 Ncert Solutions Pdf Download LINK
Jerry Bradley
8.28. What are inner transition elements? Decide which of the following atomic numbers are the atomic numbers of the inner transition elements: 29,59,74,95,102,104.
Sol: The f-block elements in which the. last electron enters into f-sub shell-are called inner-transition elements. These include lanthanoids (Z=58 to 71) and actinoids (Z=90 to 103). Thus, the elements with atomic numbers 59,95 and 102 are the? inner transition elements.
Account for the following:
(i) Copper(I) compounds are white whereas Copper (II) compounds are colored.
(ii) Chromates change their color when kept in an acidic solution.
(iii) Zn, Cd, Hg are considered as d-block elements but not as transition elements.
The chapter d and f block elements is very important from the examination perspective. It explains the elements in the groups 3-12. A detailed understanding of this chapter will help the students to differentiate between the characteristics of d and f block elements. It also explains a comparative account of lanthanoids and actinoids.
Question 5.
How would you account for the irregular variation in ionisation enthalpies (first and second) in first series of transition elements ?
Answer:
The ionisation enthalpies of the transition metals are higher than those of s-block elements and less than the elements of p-block. Thus, these are less electropositive than the elements of s-block and at the same time more electropositive than the elements belonging to p-block present in the same period. In a transition series, the ionisation enthalpies increase from left to right. However, the gaps in the values of the two successive elements are not regular.
(c) Similarly in the atomic sizes of the elements of the second and third transition series present in the same group: We know that the atomic sizes of the elements generally increase appreciably down a group. Similar trend is also expected in the elements present in the different groups of d-block.
Question 28.
What are inner transition elements? Decide which of the following atomic numbers belong to inner transition elements :
29, 59, 74, 95, 102, 104.
Answer:
The inner transition elements also called/-block elements include the series of lanthanoids (Z = 58 to 71) and actinoids (Z = 90 to 103). This means that the elements with atomic numbers 59, 95, and 102 belong to inner transition elements.