Tag: comparison of lanthanoids and actinoids

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Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Identify the incorrect statement among the following. 

  1. 4f and 5f orbitals are equally shielded.

  2. 4-Block elements show irregular and erratic chemical properties among themselves.

  3. La and Lu have partially filled d-orbitals and no other partially filled orbitals.

  4. The chemistry of various lanthanoids is very similar.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

4f and 5f orbitals are not equally shielded. 5f are poorly shielded as 5f orbitals are away from the nucleus.

Also, 5f has poor shielding effect than 4f due to the large size of f-orbital, it is more diffused.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Which of the following is not an actinoid ?

  1. Am

  2. Cm

  3. Fm

  4. Tm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

LANTHANIDES


58Ce  59Pr  60Nd  61Pm  62Sm  63Eu  64Gd  65Tb  66Dy  67Ho  68Er  69Tm  70Yb  71Lu 

ACTINIDES

 90Th 91 Pa 92 U 93 Np 94 Pu 95 Am 96 Cm 97Bk  98Cf  99Es  100 Fm 101 Md 102No  103Lr 
          
Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Which of the following is not an actinide ?

  1. Curium

  2. Californium

  3. Uranium

  4. Terbium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

LANTHANIDES


58Ce  59Pr  60Nd  61Pm  62Sm  63Eu  64Gd  65Tb  66Dy  67Ho  68Er  69Tm  70Yb  71Lu 

ACTINIDES

 90Th 91 Pa 92 U 93 Np 94 Pu 95 Am 96 Cm 97Bk  98Cf  99Es  100 Fm 101 Md 102No  103Lr 
          
Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

The first and last elements of actinides are:

  1. Actinium and Thorium

  2. Actinium and Nobelium

  3. Actinium and Mendelevium

  4. Actinium and Lawrencium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

We have 15 elements in actinides. They are from atomic number 89 to 103 Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium. Hence, from these list we could say that Actinium is the first and Lawrencium is the last element in actinides.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

5f series elements are known as_______

  1. Lanthanides

  2. Representative elements

  3. Transition elements

  4. Actinides
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Actinides are also called the 5f series.


 Filling up of the 5f orbitals after actinium (Z = 89) gives the 5f-inner transition series known as the actinoid series.

Option D is correct.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Actiniod contraction is more than lanthanold contraction because:

  1. energy of 4f and 5f orbitals are same

  2. 5f orbitals are more diffused as compared to 4f orbitals

  3. actinoids show greater range of oxidation states than lanthanoids

  4. actinoids are highly reactive
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$5f$ orbitals are bigger than $4f$ orbitals, in other words, $5f$ orbitals are more diffused thereby having the poor shielding effect. Hence have a more effective nuclear charge thereby having a small size. Hence actinide contraction is more than lanthanide contraction.

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Assertion 


The degree of complex formation in actinides decreases in the order:

     $ \ M^{4+}>MO^{2+} _{2}> M^{3+}>MO^{+} _{2} $

Reason

Actinides form complexes with $\pi $ bonding ligands such as alkyl phosphines and thioethers.

  1. Both Assertion and Reason are correct and Reason is correct explanation for Assertion.

  2. Both Assertion and Reason are correct and Reason is not correct explanation for Assertion

  3. Both Assertion is correct but Reason incorrect.

  4. Both Assertion and Reason are incorrect
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The assertion regarding the order of complex formation is correct based on charge density. The reason is also factually correct regarding bonding, but it does not explain why the specific order of complex formation occurs, as that is primarily driven by the ionic charge and size (electrostatics).

Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

Which of the following forms stable oxidation state?

  1. Ce+ , Yb+

  2. Eu + , Tb+

  3. Lu+, Gd

  4. Pr5+ ,Nd2+
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cerium (Ce) and Ytterbium (Yb) can exhibit stable +4 and +2 oxidation states respectively due to stable electronic configurations (f0 and f14), making Ce+ and Yb+ (or their related stable ions) notable in lanthanide/actinide chemistry contexts.