General Properties Of F-block
The most common and stable oxidation state shown by the majority of the lanthanoid elements in their compounds is which of the following?
Select the correct option:
Solution
+3
The lanthanoids are characterised by a strong preference for a single common oxidation state. The most stable and characteristic oxidation state of the majority of lanthanoid elements is +3, formed by the loss of the two 6s electrons and one 4f or 5d electron. This +3 state is stable because the deeply buried 4f electrons are well shielded and reluctant to take part in further bonding, so most lanthanoids form M^3+ ions and compounds such as their oxides and chlorides. A few lanthanoids show +2 or +4 states in special cases, such as Eu^2+ and Ce^4+, where these confer extra stability through half-filled or empty f-subshells, but +3 dominates. The option +1 is not a characteristic state. The option +2 occurs only exceptionally. The option +4 is also exceptional and not the general state. The dominance of the +3 state is a fundamental NCERT f-block fact. Plausibility check: the formation of M^3+ oxides and salts by nearly all lanthanoids confirms that +3 is the common stable oxidation state.
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About This Question
- Subject
- chemistry
- Chapter
- d- and f-block elements
- Topic
- general properties of f-block
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
+3
The lanthanoids are characterised by a strong preference for a single common oxidation state. The most stable and characteristic oxidation state of the majority of lanthanoid elements is +3, formed by the loss of the two 6s electrons and one 4f or 5d electron. This +3 state is stable because the deeply buried 4f electrons are well shielded and reluctant to take part in further bonding, so most lanthanoids form M^3+ ions and compounds such as their oxides and chlorides. A few lanthanoids show +2 or +4 states in special cases, such as Eu^2+ and Ce^4+, where these confer extra stability through half-filled or empty f-subshells, but +3 dominates. The option +1 is not a characteristic state. The option +2 occurs only exceptionally. The option +4 is also exceptional and not the general state. The dominance of the +3 state is a fundamental NCERT f-block fact. Plausibility check: the formation of M^3+ oxides and salts by nearly all lanthanoids confirms that +3 is the common stable oxidation state.
This easy difficulty chemistry question is from the chapter d- and f-block elements, covering the topic of general properties of f-block. It appeared in the 2025 exam.
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