The d- and f-Block Elements Mind Map

d-block elements are elements in which the differentiating electron enters the d-subshell of the penultimate shell. They are placed between the s-block and p-block elements in the periodic table.

For classification questions, first identify the block by the subshell receiving the differentiating electron, then decide whether it is a transition element by checking partial d-orbital occupancy in the atom or common ion.

Transition metals show characteristic properties such as variable oxidation states, coloured ions, paramagnetism, complex formation, catalytic activity, high enthalpy of atomisation, high melting points, and alloy formation due to involvement of d-electrons.

In reason-based answers, pair each property with its cause: variable oxidation state with ns and d-electron participation, colour with d-d transition, magnetism with unpaired electrons, and catalysis with variable oxidation state or surface adsorption.

Across a transition series, atomic and ionic radii generally decrease at first due to increasing nuclear charge, but the decrease becomes small because added d-electrons shield each other poorly. In f-block elements, poor shielding by f-electrons causes lanthanoid contraction.

For trend answers, mention both forces: increasing nuclear charge pulls electrons inward, while poor shielding by d or f electrons explains why contraction occurs and why it affects later elements.

Magnetic behaviour of transition-metal ions depends mainly on the number of unpaired electrons. Paramagnetic species have unpaired electrons, while diamagnetic species have all electrons paired.

Always find the oxidation state first, write the d-configuration of the ion, count unpaired electrons, then substitute in the spin-only formula.

Potassium permanganate and potassium dichromate are important transition-metal compounds used as strong oxidising agents, especially in acidic medium. Their reactions involve reduction of Mn(VII) or Cr(VI) to lower oxidation states.

For redox questions, mark the oxidation state of Mn or Cr first, then identify the medium and write the corresponding reduction product before balancing or explaining the observation.

Lanthanoids and actinoids are f-block elements in which differentiating electrons enter 4f and 5f orbitals respectively. Lanthanoids commonly show +3 oxidation state, while actinoids show greater oxidation-state variability.

For comparison questions, write three points clearly: orbital filled, common oxidation state, and reason for variability or contraction.