AQA · A-Level · Chemistry
Course version: 7405 · Version from Sept 2016
Transition metal characteristics of elements Ti–Cu arise from an…
Full specification wording
General properties of transition metals (A-level only): Transition metal characteristics of elements Ti–Cu arise from an incomplete d sub-level in atoms or ions.
A transition metal is a d-block element that forms at least one stable ion with a partially filled d sub-level, and that single definition does all the work.
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- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A transition metal is a d-block element that forms at least one stable ion with a partially filled d sub-level, and that single definition does all the work. Scandium is in the block but its only common ion, Sc³⁺, is 3d⁰; zinc's only common ion, Zn²⁺, is 3d¹⁰. One is empty and one is full, so neither element is a transition metal and neither shows the characteristic chemistry. Titanium through to copper all manage an ion with between one and nine d electrons. Two configurations break the filling pattern, chromium as [Ar]3d⁵4s¹ and copper as [Ar]3d¹⁰4s¹, because a half-full or full 3d sub-level is lower in energy. When ions form the 4s electrons leave first, so Fe²⁺ is [Ar]3d⁶ and Fe³⁺ is [Ar]3d⁵.
What earns the marks
- Defining a transition metal as one that forms at least one stable ion with a partially filled d sub-level.
- Quoting Sc³⁺ as 3d⁰ or Zn²⁺ as 3d¹⁰ when explaining why those two elements are excluded.
- Stating the correct configurations [Ar]3d⁵4s¹ for chromium and [Ar]3d¹⁰4s¹ for copper.
- Removing the 4s electrons before the 3d electrons when writing the configuration of an ion.
Common mistakes and how to put them right
Saying a transition metal has a partially filled d sub-level in the atom, which wrongly admits scandium (atom is 3d¹) and wrongly excludes copper (atom is 3d¹⁰).
Put it right by specifying it must form a stable ion with a partially filled d sub-level.
Writing Fe³⁺ as [Ar]3d³4s² by taking electrons from 3d before 4s.
Put it right by removing 4s electrons first.
Giving chromium as [Ar]3d⁴4s² and copper as [Ar]3d⁹4s².
Put it right by using the anomalous half-full and full 3d configurations.
Claiming scandium is excluded because it has no d electrons, when the neutral atom is [Ar]3d¹4s².
Put it right by referencing the Sc³⁺ ion.
Exam tips
- Use the word ion in the definition, because atom alone is incorrect and will not score.
- Write the full [Ar] configuration rather than a shorthand and check the electrons total the atomic number.
- If asked about scandium or zinc, name the specific ion and its configuration as your evidence.
Try the lesson
The start of the General properties of transition metals (A-level only): Transition metal characteristics of elements Ti–Cu arise from an incomplete d sub-level in atoms or ions. lesson, made from checked teaching notes for this specification point.
Have a go first
Which electron configuration shows a Ti²⁺ ion with an incomplete d sub-level?
Listen
A transition metal is a d-block element that forms at least one stable ion with a partially filled d sub-level, and that single definition does all the work. Scandium is in the block but its only common ion, Sc³⁺, is 3d⁰; zinc's only common ion, Zn²⁺, is 3d¹⁰. One is empty and one is full, so neither element is a transition metal and neither shows the characteristic chemistry. Titanium through to copper all manage an ion with between one and nine d electrons. Two configurations break the filling pattern, chromium as [Ar]3d⁵4s¹ and copper as [Ar]3d¹⁰4s¹, because a half-full or full 3d sub-level is lower in energy. When ions form the 4s electrons leave first, so Fe²⁺ is [Ar]3d⁶ and Fe³⁺ is [Ar]3d⁵. A strong answer earns marks for these points. Defining a transition metal as one that forms at least one stable ion with a partially filled d sub-level. Quoting Sc³⁺ as 3d⁰ or Zn²⁺ as 3d¹⁰ when explaining why those two elements are excluded. Stating the correct configurations [Ar]3d⁵4s¹ for chromium and [Ar]3d¹⁰4s¹ for copper. Removing the 4s electrons before the 3d electrons when writing the configuration of an ion. A common slip: Saying a transition metal has a partially filled d sub-level in the atom, which wrongly admits scandium (atom is 3d¹) and wrongly excludes copper (atom is 3d¹⁰). Instead, specifying it must form a stable ion with a partially filled d sub-level. Exam tip: Use the word ion in the definition, because atom alone is incorrect and will not score.
See it
![A flowchart starting from a d-block element, which leads to a decision: does it form at least one stable ion with a partially filled d sub-level? If yes, it is a transition metal; if no, it is not a transition metal. The 'not a transition metal' branch gives two examples: Sc³⁺ is 3d⁰ and Zn²⁺ is 3d¹⁰. The 'transition metal' branch states that titanium to copper have an ion with between one and nine d electrons, and that the 4s electrons leave first when ions form, giving Fe²⁺ as [Ar]3d⁶ and Fe³⁺ as [Ar]3d⁵.](https://xnnrgnazirrqvdgfhvou.supabase.co/storage/v1/object/public/lesson-media/f8494eb8-4369-433f-beef-9f9cd68da880/diagram-cd501554fb50.svg)
Key words
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transition metal
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scandium and zinc exceptions
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chromium and copper anomalies
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4s lost first
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See every definition
- transition metal
- A d-block element that forms at least one stable ion with a partially filled d sub-level.
- scandium and zinc exceptions
- Neither element is a transition metal because Sc³⁺ is 3d⁰ and Zn²⁺ is 3d¹⁰, one empty and one full.
- chromium and copper anomalies
- Their configurations break the filling pattern, chromium as [Ar]3d⁵4s¹ and copper as [Ar]3d¹⁰4s¹, because a half-full or full 3d sub-level is lower in energy.
- 4s lost first
- When ions form the 4s electrons leave first, so Fe²⁺ is [Ar]3d⁶ and Fe³⁺ is [Ar]3d⁵.
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