Question 1

What is the difference between 4f and 5f atomic orbitals?&#10;A) 4f atomic orbitals are more core-like than 5f atomic orbitals&#10;B) Both 4f and 5f atomic orbitals are destabilized and very diffuse.&#10;C) 5f atomic orbitals are poorly shielded from the nucleus in comparison to 4f atomic orbitals.

Accepted Answer

4f orbitals are more core-like and are closer to the nucleus compared to 5f orbitals, which are more extended and diffuse.

Question 2

What is the most common oxidation state for lanthanoid elements?&#10;A) +2&#10;B) +3&#10;C) +4

Accepted Answer

The most common oxidation state for lanthanoid elements is +3. This is because in most lanthanides, the removal of three electrons—two from the 6s subshell and one from the 4f subshell—results in a stable electron configuration.

Question 3

Identify the correct statement about lanthanoids. A) The ionic radii of Ln³⁺decrease from left to right. B) The first ionization energy for lanthanoids decreases from left to right. C) The 4f electrons are important in the formation of metallic bond

Accepted Answer

The ionic radii of lanthanoids decrease from left to right across the period, a phenomenon known as the lanthanide contraction. This occurs due to the poor shielding effect of the 4f electrons, which leads to an increase in effective nuclear charge across the series.

Question 4

Select the correct statement:&#10;A) Lanthanoid cations are soft Lewis acids.&#10;B) Lanthanoid cations can sustain high coordination numbers of seven and above.&#10;C) Lanthanoid complexes show strong ligand field effects.

Accepted Answer

Lanthanoid cations can indeed sustain high coordination numbers, often seven and above, due to their relatively large size and the ability to accommodate multiple ligands around them.

Question 5

What types of binary ionic compounds are well-known for all lanthanides?&#10;A) oxides, halides, hydrides, and nitrides&#10;B) hydrides and nitrides only&#10;C) oxides and halides only

Accepted Answer

Lanthanides form a variety of binary ionic compounds, including oxides, halides (such as fluorides, chlorides, bromides, and iodides), hydrides, and nitrides, showcasing their versatile chemical behavior.

Question 6

Find the correct statement(s) on lanthanoid organometallic chemistry.
(i) The bonding in organolanthanoid compounds is predominantly ionic.
(ii) Lanthanoids frequently form carbonyl clusters with metals in low oxidation states.
(iii) Electronic effects dominate over steric effects in reactivity and structural considerations.

A) All of them are correct.
B) (ii) and (i)
C) (i) only.

Accepted Answer

The bonding in organolanthanoid compounds is predominantly ionic due to the electropositive nature of lanthanoids. Lanthanoids do not frequently form carbonyl clusters, and steric effects often play a significant role in their chemistry, making (ii) and (iii) incorrect.

Question 7

In comparison to lanthanoids, actinoids:&#10;A) are more reducing metals.&#10;B) have more accessible oxidation states.&#10;C) are more abundant in nature.

Accepted Answer

Actinoids exhibit a wider range of oxidation states compared to lanthanoids. This is due to the fact that their 5f, 6d, and 7s subshells are very close in energy, allowing electrons to be lost or gained from any of these orbitals, leading to multiple oxidation states.

Question 8

The highest oxidation state for actinoids is:&#10;A) +3&#10;B) +4&#10;C) +6

Accepted Answer

Actinoids can exhibit a variety of oxidation states, but the highest oxidation state they can achieve is +6, as seen in elements like Uranium (U) in the compound UF6 (uranium hexafluoride).

Question 9

In the electronic spectra of actinoid compounds the following transitions can be observed:&#10;A) transitions involving only 5f electrons/orbitals&#10;B) transitions involving 5f, 6d and ligand-to-metal charge transfer.&#10;C) transitions involving 6d and ligand-to metal charge transfer.

Accepted Answer

Actinoid compounds can exhibit electronic transitions involving 5f and 6d orbitals, as well as ligand-to-metal charge transfer transitions due to their complex electronic structures and the involvement of multiple orbitals.

Question 10

Find the correct statement:&#10;A) Pu(VI) is more stable than U(VI).&#10;B) Np in all oxidation states prefers forming bonds to hard donor atoms.&#10;C) After americium, the stability of +6 oxidation state increases to the right of actinoid series.

Accepted Answer

The answer of Find the correct statement:&#10;A) Pu(VI) is more...

Deck 23: The F-Block Metals