+91-8076753736 support@wiredfaculty.com
logo
logo

Sponsor Area

The D-And-f-Block Elements

Question
CBSEENCH12007117
Wired Faculty App

Compare the chemistry of actinides with that of the lanthanoids with special reference to:
(i) electronic configuration, (ii) atomic and ionic sizes, (iii) oxidation state (iv) chemical reactivity.

Solution

Characteristics

Lanthanoids

Actinides

(a) Electronic configuration

It may be represented by [Xe]4fx 5dy 6s2, where x varies from 0 to 14 and y = 0 or 1.

It may be represented by [Rn]5fx 6dy 7s2,where x varies from 0 to 14 and y = 0 or 1.

(b)    Oxidation state

 

Show +3 oxidation state only except in few cases where it is +2 or +4. They never show more than +4 state.

Show higher oxidation states such as +4, +5, +6, +7 also in addition to +3.

 

(c) atomic and ionic sizes

 

The ionic radii of M3+ ions in lanthanoids series show a regular decrease in size of ions with increase in atomic number. This decrease is known as lanthanoid contraction.

There is a greater and gradual decrease in the size of atoms or M3+ ions across the series. This greater decrease is known as actinoid contraction.

 

(d)    Chemical reactivity

These are less reactive metals and form oxides, sulphides, nitrides, hydroxides and halides etc. These also form H2 with acids. They show a lesser tendency for complex formation

These are highly reactive metals especially when are in finely divided state. They form a mixture of oxide and hydride by action of boiling water. They combine with non-metals even at moderate temperature. They show a greater tendency for complex formation.

Some More Questions From The d-And-f-Block Elements Chapter

Explain why Cu+ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?

The outer electronic configuration of copper is 3d10 4s1, yet it is considered transition element. Why?

Why the melting points of transition elements are high?

Why Zn, Cd and Hg are not regarded as transition elements?

Name the first element of 3rd transition series.

Though copper, silver and gold have completely filled sets of d-orbitals yet they are considered as transition metals. Why?

Why are transition elements so named?

Why are transition elements known as d-block elements?

Mock Test Series

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation