d and f BLOCK ELEMENTS

What is the electronic configuration of the element with atomic number 61 (Promethium)?

• [Xe] 4f^4 6s^2
• [Xe] 4f^6 6s^2
• [Xe] 4f^5 5d^1 6s^1
• [Xe] 4f^5 6s^2

How does the chemical reactivity of early actinoids (e.g., Ac, Th, Pa, U) compare to that of lanthanoids?

• Early actinoids are less reactive than lanthanoids.
• Early actinoids are generally more reactive than lanthanoids, showing greater similarity to transition metals.
• Reactivity is similar for both series.
• Lanthanoids are more reactive due to their larger atomic sizes.

How do the common oxidation states of actinoids compare to those of lanthanoids?

• Both primarily show +3 and +4.
• Lanthanoids primarily show +3, with some showing +2 or +4. Actinoids show a wider range of oxidation states, including +3, +4, +5, +6, and +7.
• Actinoids primarily show +3, with some showing +4 or +5.
• Lanthanoids show more variable oxidation states than actinoids.

In what key ways do the electronic configurations of actinoids differ from those of lanthanoids?

• Actinoids fill 6d orbitals, while lanthanoids fill 4f orbitals.
• Actinoids fill 5f orbitals, while lanthanoids fill 4f orbitals. Actinoid configurations are often more variable and less predictable.
• Lanthanoids have more variable configurations.
• There is no significant difference.

Which lanthanoid elements are known to commonly exhibit a +2 oxidation state, and what feature of their electronic configuration contributes to this?

• Ce (Cerium) and Pr (Praseodymium); achieving a stable [Xe] core.
• Eu (Europium) and Yb (Ytterbium); achieving stable filled 4f^7 (Eu^2+) or filled 4f^14 (Yb^2+) subshells.
• All lanthanoids can exhibit +2.
• Only Samarium (Sm); due to its specific atomic number.