Why do transition elements show variable oxidation states?
Answer
Transition elements show variable oxidation states because the energies of their (n−1)d and ns orbitals are very close, so both sets of electrons can take part in bonding.
The working
Reason
In transition metals the (n−1)d and outermost ns orbitals have nearly equal energies, so a variable number of electrons from both can be lost during bonding.
Small energy gaps
Because removing successive d electrons needs only small extra energy, several different oxidation states become possible for the same element.
Example
Manganese shows states from +2 up to +7 (as in MnO₄⁻), and iron commonly shows +2 and +3.
Contrast
In s-block metals, only the ns electrons are available, so they show a single fixed oxidation state.
Stuck on something else?
Type your own doubt into the solver and get the full working in seconds — free, for physics, chemistry, maths and biology.
Open the solverRelated doubts