Oxidation State of Transition Metals - NEET Notes, Formula & Common Mistakes
Oxidation StateRedox ReactionsNEET ChemistryNEET 2025Transition MetalsD-block ElementsVariable Oxidation States
Oxidation State of Transition Metals - NEET Notes, Formula & Common Mistakes
Redox Reactions·2 min read·NEET 2026
What NEET Asks
NEET frequently tests the calculation of oxidation states in various compounds and complex ions involving transition metals.
Questions often involve identifying reasons for variable oxidation states or comparing the stability of different oxidation states.
Expect 1-2 direct questions from Redox Reactions, often including d-block elements.
Key Points
Transition metals exhibit variable oxidation states due to the involvement of both (n-1)d and ns electrons in bonding.
The most common oxidation state for first-row transition metals is +2 (from the loss of 4s electrons).
Higher oxidation states are achieved by involving the (n-1)d electrons.
The highest oxidation state generally corresponds to the sum of ns and (n-1)d electrons (up to Group 7, i.e., Mn).
Stability of oxidation states varies across the period and down the group (e.g., higher OS more stable for heavier elements).
Oxidation state of an element in its uncombined state is always zero.
Standard oxidation states: Group 1 (+1), Group 2 (+2), F (-1), O (-2, except in peroxides -1, superoxides -1/2, OF2 +2), H (+1, except in metal hydrides -1).
Must-Know Formula / Reaction
Sum of oxidation states = Total charge on the species
∑(Oxidation state of each atom × number of atoms) = Charge
Students often forget the charge of common ligands (e.g., CN⁻ is -1, H₂O is 0) when calculating oxidation states in coordination compounds.
Don't confuse variable oxidation states of transition metals with fixed oxidation states of elements like Group 1 or 2 metals.
Assuming oxygen is always -2; overlooking exceptions like peroxides (H₂O₂, Na₂O₂) or superoxides (KO₂).
Rapid Revision
Transition metals show variable OS due to (n-1)d and ns electron participation. Calculate OS by setting the sum of individual OS to the total charge. Remember exceptions for O and H. Highest OS often matches total d+s electrons up to Mn.
Frequently Asked Questions
Why do transition metals exhibit variable oxidation states?▾
Transition metals exhibit variable oxidation states primarily because their (n-1)d and ns orbitals are very close in energy. This allows both the ns electrons and a varying number of (n-1)d electrons to participate in bonding, leading to multiple stable oxidation states.
What is the most common oxidation state for first-row transition metals?▾
The most common and stable oxidation state for first-row transition metals is generally +2. This arises from the loss of the two electrons from the 4s orbital, which are typically lost first during ionization.
How is the highest oxidation state determined for transition metals?▾
For transition metals up to manganese (Group 7), the highest oxidation state observed often corresponds to the sum of the electrons in the ns and (n-1)d orbitals. For example, Mn has 4s²3d⁵ configuration, giving a maximum oxidation state of +7.
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