D and F-block Element Question-Answer | MCQ test

The d and f Block Elements Chemistry class 12

1. The elements present between s-block and p-block elements (i.e. between group 2 and 13) are known as d-block or transition elements.
2.  d-block elements are those elements in which last electron enters the d-orbital of penultimate (n-1) shell.
3.  Transition elements are those elements in which d-orbital is incompletely filled in their elementary form or in most common oxidation state.
4.  Zn, Cd, Hg are not considered as Transition element because they have d¹⁰ configuration in elementary as well as in common oxidation state.
5. There are four transition series each of 10 elements:
   1. First transition series: It involves filling of 3d-orbitals. It starts from scandium (Z = 21) to zinc (Z = 30).
   2.  Second transition series: It involves filling of 4d-orbitals. It starts from yttrium (Z=39) to cadmium (Z = 48).
   3. Third transition series: It involves filling of 5d-orbitals. The first element of this series is lanthanum (Z = 57). It is followed by 14 elements called lanthanides which involve the filling of 4f-orbitals. The next nine elements from hafnium (Z = 72) to mercury (Z = 80) belong to third transition series.
   4. Fourth transition series: it involves filling of 6d-orbital.This is a radioactive series.
6. All the transition elements are metallic in nature, good conductors, of heat and electricity; show a gradual decrease in electropositive character in moving across a period. Due to strong metallic bonds, these metals are hard, possess high densities, high enthalpies of atomisation, high melting and boiling points and form alloys with other metals.
7. The melting point of these first increases to maximum and then gradually decreases towards the end of the series. The strength of metallic bonds is roughly related to number of half-filled d-orbitals.
8. The radii of ions, having the same charge and magnitude, in a given series decreases progressively with increase in atomic number. This is because of poor shielding effect of d-electrons.
9. Ionisation energies of transition elements are higher than those of s-block elements but lower than p-block elements. It generally increases from left to right in the series.
10.  Transition metals exhibit a variety of oxidation states. The variable oxidation states of transition metals are due to involvement of ns and (n – 1 )d- electrons in bonding.
11. Most of the transition metals are sufficiently electropositive. They react with mineral acids liberating H₂ gas.
12.  Transition elements and many of their compounds are paramagnetic,
13.  Formation of coloured compounds (both in solid state as well as in aqueous solution) is another very common characteristics of transition metals. This is due to absorption of some radiation from visible light to cause d-d transition of electrons in transition metal atom.
14. The transition elements have the ability to form complexes. This is due to-
    •  Small size
    • Highly charged ions, and
    •  Availability of vacant d-orbitals.

15.  Most of transition metals, ions and their compounds act as catalyst in variety of reactions. This is due to –
    • large surface area
    • free valency on the surface
    • formation of weak intermediate complex
16. Transition metals form large number of interstitial compounds.
17. A large number of alloys are formed by transition metals. It is due to almost similar atomic size where atoms mutually substitute their positions easily in crystal lattices.
18.  The oxides of transition metals in lower oxidation states are generally basic in nature and those in, higher oxidation states are amphoteric or acidic in nature.
19. F-block Elements are those elements in which last electron enters the f-orbital of antepenultimate(n-2) shell. The f-block elements are called inner-transition elements.
20.  The f -block elements have been divided in two series depending upon the fact whether the last electron (differentiating electron) enters 4f- orbitals or 5f-orbitals and accordingly called lanthanides or actinides respectively
21.  Actinides show several oxidation states but + 3 oxidation state is most common. The highest oxidation state shown by actinides is + 7.
22.  Properties of the lanthanides:
    1.  General electronic configuration is [Xe] 4f^1-14 5d^0-1 6s².
    2. The metals are silvery-white in colour. They are malleable, ductile, have low tensile strength and are good conductors of heat and electricity.
    3. They have relatively high density and possess high melting points.
    4.  The lanthanides exhibit a principle oxidation state of + 3. However, some elements also exhibit + 2 (Eu²⁺) and + 4 (Ce⁴⁺)oxidation states.
    5.  Many of the lanthanide ions are coloured due to the electronic transition between different 4 f-levels.
    6. The majority of the lanthanide ions exhibit paramagnetism due to the presence of unpaired electrons. The lanthanide ions that do not exhibit paramagnetism are those with either no 4f-electrons, e. g., La³⁺ and Ce⁴⁺ or with a completed 4f-level, e.g., Yb²⁺ and Lu³⁺.
    7. The lanthanides readily tarnish in air and bum to give trioxides (except cesium, which forms Ce0₂).
    8.  The oxides and hydroxides of the lanthanides are basic in character.
    9.  The lanthanide compounds are generally predominantly ionic.
23.  This gradual decrease in atomic size across the first f- transition element series is called Lanthanide contraction.
24. Properties of actinides:
    1. General electronic configuration is [Rn] 5f^0-14 6ds^0-1 7s².
    2.  The elements are all silvery-white metals.
    3. The melting points of the actinides are moderately high.
    4.  The ionic size of the actinides decreases gradually along the series.
    5.  The actinides have the ability to exhibit several oxidation states. However, +4 oxidation state is preferred in actinides.
    6. Some actinoid elements can exist in + 6 oxidation state, e.g., uranium, neptunium and plutonium.
    7. Many actinoid elements are radioactive. The elements beyond uranium are man-made.
    8. The actinides have a much greater tendency to form complexes than lanthanides.

D-block element having ns¹ configuration

1. d-block elements having ns¹ configuration
   • Cr = 3d⁵ 4s¹ 
   • Cu = 3d¹⁰ 4s¹
   • Nb = 4d⁴ 5s¹
   • Mo =  4d⁵ 5s¹
   • Tc =  4d⁶ 5s¹
   • Ru =  4d⁷ 5s¹
   • Rh =  4d⁸ 5s¹
   • Ag =  4d¹⁰ 5s¹
   • Au =  5d¹⁰ 6s¹
   • Pd  =  4d¹⁰ 5s⁰
   • Pt =  5d⁹ 6s¹

2. Code to remember :- NCC me Teri RRePot Aa Aegi
3. (N = Nb) (C = Cr) (C = Cu) (me = Mo) (R = Ru) (Re = Rh) (pot = Pt) (Aa = Au) (Aegi = Ag)

D and f-block element Most important Question Answers Chemistry Class 12

Q1. What are D- block elements?

Show Answer

Q2. What are transition elements?

Show Answer

Q3. Zn, Cd and Hg are not considered as transition element. why?

Show Answer

Q4. What is the position of Transition or d-block elements?

Show Answer

Q5.Why are d-block elements also known as Transition elements?

Show Answer

Q6. What are Typical transition elements?

Show Answer

Q7. What are non-typical transition elements?

Show Answer

Q8. What are coinage metals?

Show Answer

Q9.What is penultimate shell?

Show Answer

Q10. What is antepenultimate shell?

Show Answer

Q11. What are f-block elements?

Show Answer

Q12. What is the position of f-block elements?

Show Answer

Q13. What are inner-transition elements?

Show Answer

Q14. What are Lanthanides?

Show Answer

Q15.What are Actinides?

Show Answer

Q16. What are trans-uranium elements?

Show Answer

Q17.