Intermediate Topic 670 of 1102 Inorganic Chemistry
Variable Oxidation States
Transition metals can lose different numbers of d and s electrons.
In-depth explanation of Variable Oxidation States
Transition metals can lose different numbers of electrons from their ns and (n-1)d subshells, which have similar energies and lie close together. This gives many oxidation states for each element, and the highest usually equals the group number up to manganese, which reaches +7. Higher oxidation states are stabilized by electronegative ligands such as oxide and fluoride, which accept electron density from the metal. Iron commonly occurs as Fe2+ and Fe3+, copper as Cu+ and Cu2+, and chromium as Cr2+, Cr3+ and Cr6+. This variety makes many of these metals useful redox catalysts.
Going deeper: Variable Oxidation States
Key ideas: In the first row, oxidation states differ by one unit because (n-1)d and ns electrons have similar energies: Mn shows +2 to +7. Highest state equals the group number up to Mn (+7), then falls. Stability of +2 rises across the series; the highest states appear in oxides and fluorides (MnO4-, CrO4 2-, OsO4). Lower states occur in carbonyls. In p-block, states differ by two instead.
Common mistakes and connections: Students believe all transition metals show +2 because of 4s loss; Sc shows only +3 and Zn only +2. Higher oxidation states are oxidizing in acid (MnO4-), lower states reducing (Cr2+). Higher states are more stable down a group, opposite to p-block. Links to redox titrations, Latimer diagrams and colored ions.
Visualization of Variable Oxidation States
Highest oxidation state across the first row peaks at +7 for manganese, then falls as d electrons become too tightly held. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Manganese shows oxidation states from +2 in Mn2+ to +7 in the permanganate ion, MnO4-.
Frequently asked questions about Variable Oxidation States
What is Variable Oxidation States?
Transition metals can lose different numbers of d and s electrons.
Is Variable Oxidation States a beginner, intermediate or advanced topic?
Variable Oxidation States is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Variable Oxidation States?
Study these earlier topics in Inorganic Chemistry first: Xenon Compounds, Uses of Noble Gases, Transition Metals General.
What comes after Variable Oxidation States?
The next topics in Inorganic Chemistry are Colored Ions and Catalytic Behavior of Transition Metals.
Can I practise Variable Oxidation States with quizzes?
Yes. The interactive lesson includes a self-check question on Variable Oxidation States, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Variable Oxidation States fits in Inorganic Chemistry
Variable Oxidation States is topic 55 of 113 in Inorganic Chemistry.