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General Properties of Transition Metals

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Student-friendly explanation

How to write this in exams

1
Start with the exact idea
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.
2
Then show how to use it
For any property question, write the ion's d-electron count, check unpaired electrons or incomplete d-orbitals, then connect the observation to the correct cause and example.
3
Add one concrete example
Fe shows +2 and +3 oxidation states, Cu₂⁺ salts are often coloured, Ni forms complexes such as [Ni(CN)4]2-, and finely divided iron acts as a catalyst in the Haber process.
4
Avoid this incomplete answer
A realistic wrong answer is claiming all transition-metal ions are coloured. d0 and d10 ions are generally colourless because d-d transitions are not possible in the usual sense.

Definition

Example

Fe shows +2 and +3 oxidation states, Cu₂⁺ salts are often coloured, Ni forms complexes such as [Ni(CN)4]2-, and finely divided iron acts as a catalyst in the Haber process.

Rule to remember

Property-cause pattern: variable oxidation state arises from comparable ns and (n-1)d energies; paramagnetism depends on unpaired electrons; colour generally requires partially filled d-orbitals; complex formation is favoured by small size, charge, and available orbitals.

Memory hook

Variable state, colour, magnetism, complexes, catalyst, alloys: most answers begin with d-electrons.

Examples and method

Worked example

Explain why Ti₃⁺ is coloured but Sc₃⁺ is colourless. Ti₃⁺ has 3d1 configuration, so d-d transition is possible. Sc₃⁺ has 3d0 configuration, so no d-d transition occurs and it is colourless.

Method to apply

For any property question, write the ion's d-electron count, check unpaired electrons or incomplete d-orbitals, then connect the observation to the correct cause and example.

Diagram support

A comparison table linking property, cause, and example is more useful than a structural diagram for this concept.

How CBSE asks it

CBSE questions often ask for reasons for colour, magnetic nature, variable oxidation states, alloy formation, or catalytic behaviour, usually with a named ion or metal.

Avoid common mistakes

Common confusion

Students often give one reason for all properties. Colour is mainly linked to d-d transition in partly filled d-orbitals, while paramagnetism is linked to unpaired electrons. These are related but not identical explanations.

Common wrong answer

A realistic wrong answer is claiming all transition-metal ions are coloured. d0 and d10 ions are generally colourless because d-d transitions are not possible in the usual sense.

Exam tip

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.

Quick check

Why do many transition-metal ions show colour?

Many transition-metal ions have partially filled d-orbitals. Absorption of visible light can promote d-electrons between split d-levels, and the transmitted or reflected complementary colour is observed.

Answer writing and exam use

1-mark answer

2-mark answer

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. Property-cause pattern: variable oxidation state arises from comparable ns and (n-1)d energies; paramagnetism depends on unpaired electrons; colour generally requires partially filled d-orbitals; complex formation is favoured by small size, charge, and available orbitals. Fe shows +2 and +3 oxidation states, Cu₂⁺ salts are often coloured, Ni forms complexes such as [Ni(CN)4]2-, and finely divided iron acts as a catalyst in the Haber process.

3-mark answer

The small energy difference between ns and (n-1)d orbitals allows different numbers of electrons to participate in bonding. Partially filled d-orbitals cause d-d transitions responsible for many colours, unpaired electrons cause paramagnetism, and vacant or suitable d-orbitals support complex formation. Their similar atomic sizes and metallic bonding also favour alloy formation. Property-cause pattern: variable oxidation state arises from comparable ns and (n-1)d energies; paramagnetism depends on unpaired electrons; colour generally requires partially filled d-orbitals; complex formation is favoured by small size, charge, and available orbitals. Explain why Ti₃⁺ is coloured but Sc₃⁺ is colourless. Ti₃⁺ has 3d1 configuration, so d-d transition is possible. Sc₃⁺ has 3d0 configuration, so no d-d transition occurs and it is colourless. CBSE questions often ask for reasons for colour, magnetic nature, variable oxidation states, alloy formation, or catalytic behaviour, usually with a named ion or metal. A realistic wrong answer is claiming all transition-metal ions are coloured. d0 and d10 ions are generally colourless because d-d transitions are not possible in the usual sense.

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