Write down the electronic configuration of Co 2 +

Co 2 + is formed by the loss of two electrons from the 4 s orbital of the cobalt atom. It has now a total of 25 electrons. Therefore, the electronic configuration can be given as 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 7 or Ar 3 d 7 .

Name the members of the lanthanoid series which exhibit + 4 oxidation state and those which exhibit + 2 oxidation states. Try to correlate this type of behaviour with the electronic configuration of these elements.

The lanthanoids that exhibit + 4 oxidation state are cerium, terbium, promethium and neodymium. Cerium and terbium shows + 4 oxidation. This can be explained in the terms of extra stability of half filled and completely filled 4 f sub-shell respectively in their + 4 oxidation state. Promethium and neodymium shows + 4 oxidation stable because both these tetra positive ions are excess of one or two electrons respectively from the necessary 4 f -sub-shell stable configuration. The lanthanoids that exhibit + 2 oxidation states are europium, ytterbium, samarium and thulium. The + 2 oxidation state of europium and ytterbium can be explained in terms of the extra stability of half filled and completely filled 4 f -sub-shell. Similarly, the + 2 oxidation states of samarium and thulium is because these ions are short of one electron from the necessary half filled and completely filled stable configurations.

E M B I B E

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 30

EASY

12th West Bengal Board

IMPORTANT

Earn 100

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

Important Questions on d- and f-Block Elements

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 31

What is meant by 'disproportionation'? Give two examples of disproportionation reaction in aqueous solution.

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 32

Calculate the number of unpaired electrons in following gaseous ions:

{Mn}^{3 +}, {Cr}^{3 +}, V^{3 +}, and {Ti}^{3 +}

. Which one of these is the most stable in aqueous solution?

EASY

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 33

Write the electronic configurations of the elements with the atomic numbers

61, 91, 101

and

109

.

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 34

What are alloys? Name an important alloy which contains some lanthanoid metals. Mention its uses.

EASY

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 35

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

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 36

The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.

EASY

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 37

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.

EASY

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 8 - d- and f-Block Elements>REVIEW EXERCISES>Q 38

Use Hund's rule to derive the electronic configuration of