AQA · A-Level · Chemistry
Course version: 7405 · Version from Sept 2016
The characteristic properties include: complex formation formation of…
Full specification wording
General properties of transition metals (A-level only): The characteristic properties include: complex formation formation of coloured ions variable oxidation state catalytic activity.
Four properties define transition metal chemistry, tracing back to a partially filled 3d sub-level.
Checked against the AQA 7405 specification (opens in a new tab) on .
- Point 2 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Four properties define transition metal chemistry, tracing back to a partially filled 3d sub-level. The ions are small and highly charged, accepting lone pairs from ligands to form complexes. The d orbitals are split into two energy levels by ligands; because they are partly filled, an electron can be promoted across the gap by visible light, making the ions coloured. The 4s and 3d sub-levels lie close in energy, allowing different numbers of electrons to be lost for variable oxidation states. This ability, plus adsorption onto surfaces, makes them effective catalysts. While zinc and scandium do form complexes, they lack the partially filled d sub-level required for coloured ions, variable oxidation states, and catalytic activity.
What earns the marks
- Naming each property: complex formation, coloured ions, variable oxidation state and catalytic activity.
- Linking the properties of coloured ions, variable oxidation states, and catalytic activity back to the partially filled d sub-level.
- Naming the three changes that alter the colour of a complex: oxidation state, ligand and co-ordination number.
- Providing a correct example, such as [Cu(H₂O)₆]²⁺ being blue or iron catalysing the Haber process.
Common mistakes and how to put them right
Listing high melting point or good electrical conductivity as a characteristic property, which is true of metals generally.
Put it right by focusing on the four specific transition metal properties.
Naming a change of concentration as a way to change the colour of a complex.
Put it right by specifying a change in ligand, oxidation state or co-ordination number.
Saying transition metals are coloured.
Put it right by stating it is their ions and complexes that are coloured.
Claiming zinc or scandium do not form complexes.
Put it right by noting they do form complexes but lack the other three characteristic properties.
Exam tips
- If the question asks for three ways to change a complex's colour, answer exactly: change the ligand, the oxidation state or the co-ordination number.
- Attach a named example to each property, because a bare list usually scores less than a list with evidence.
- Use the partially filled d sub-level as your explanation for colour, variable oxidation states, and catalytic activity.
Try the lesson
The start of the General properties of transition metals (A-level only): The characteristic properties include: complex formation formation of coloured ions variable oxidation state catalytic activity. lesson, made from checked teaching notes for this specification point.
Have a go first
Which property is characteristic of transition metals because they can form ions with different charges?
Listen
Four properties define transition metal chemistry, tracing back to a partially filled 3d sub-level. The ions are small and highly charged, accepting lone pairs from ligands to form complexes. The d orbitals are split into two energy levels by ligands; because they are partly filled, an electron can be promoted across the gap by visible light, making the ions coloured. The 4s and 3d sub-levels lie close in energy, allowing different numbers of electrons to be lost for variable oxidation states. This ability, plus adsorption onto surfaces, makes them effective catalysts. While zinc and scandium do form complexes, they lack the partially filled d sub-level required for coloured ions, variable oxidation states, and catalytic activity. A strong answer earns marks for these points. Naming each property: complex formation, coloured ions, variable oxidation state and catalytic activity. Linking the properties of coloured ions, variable oxidation states, and catalytic activity back to the partially filled d sub-level. Naming the three changes that alter the colour of a complex: oxidation state, ligand and co-ordination number. Providing a correct example, such as [Cu(H₂O)₆]²⁺ being blue or iron catalysing the Haber process. A common slip: Listing high melting point or good electrical conductivity as a characteristic property, which is true of metals generally. Instead, focusing on the four specific transition metal properties. Exam tip: If the question asks for three ways to change a complex's colour, answer exactly: change the ligand, the oxidation state or the co-ordination number.
Key words
Say what each word means before you turn the card.
Complex formation
Try answering aloud or in your head before turning the card.
Variable oxidation state
Try answering aloud or in your head before turning the card.
Catalytic activity
Try answering aloud or in your head before turning the card.
Partially filled d sub-level
Try answering aloud or in your head before turning the card.
See every definition
- Complex formation
- The process in which ions that are small and highly charged accept lone pairs from ligands.
- Variable oxidation state
- Arises because the 4s and 3d sub-levels lie close in energy, allowing different numbers of electrons to be lost.
- Catalytic activity
- Effective catalysis that comes from the ability to adopt variable oxidation states plus adsorption onto surfaces.
- Partially filled d sub-level
- Required for coloured ions, variable oxidation states and catalytic activity, and lacking in zinc and scandium.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of General properties of transition metals (A-level only): The characteristic properties include: complex formation formation of coloured ions variable oxidation state catalytic activity.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge