Why is zinc not a transition metal?

Its only ion, Zn²⁺, is [Ar]3d¹⁰, so the d sub-level is full.

Why is scandium not a transition metal?

Its only ion, Sc³⁺, has no d electrons, so the d sub-level is empty.

Why is copper a transition metal?

Cu²⁺ is [Ar]3d⁹, an incomplete d sub-level, even though Cu atoms are 3d¹⁰.

Give the electron configuration of Fe³⁺.

[Ar]3d⁵ (the 4s electrons are lost first).

Name four characteristic properties of transition metals.

Complex formation, coloured ions, variable oxidation state and catalytic activity.

Why do transition metals show variable oxidation states?

The 4s and 3d sub-levels are close in energy, so electrons from both can be lost.

A molecule or ion that forms a co-ordinate bond with a transition metal ion by donating a pair of electrons.

What is a co-ordinate bond?

A covalent bond in which both shared electrons come from one species, the ligand.

A central metal atom or ion surrounded by ligands.

What is the co-ordination number?

The number of co-ordinate bonds to the central metal atom or ion.

General properties of transition metalsAQA A-Level Chemistry: Flashcards

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What is a transition metal?

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What is a transition metal?: A d-block element that forms at least one ion with an incomplete d sub-level.
Why is zinc not a transition metal?: Its only ion, Zn²⁺, is [Ar]3d¹⁰, so the d sub-level is full.
Why is scandium not a transition metal?: Its only ion, Sc³⁺, has no d electrons, so the d sub-level is empty.
Why is copper a transition metal?: Cu²⁺ is [Ar]3d⁹, an incomplete d sub-level, even though Cu atoms are 3d¹⁰.
Give the electron configuration of Fe³⁺.: [Ar]3d⁵ (the 4s electrons are lost first).
Give the electron configuration of Cr.: [Ar]3d⁵4s¹.
Name four characteristic properties of transition metals.: Complex formation, coloured ions, variable oxidation state and catalytic activity.
Why do transition metals show variable oxidation states?: The 4s and 3d sub-levels are close in energy, so electrons from both can be lost.
What is a ligand?: A molecule or ion that forms a co-ordinate bond with a transition metal ion by donating a pair of electrons.
What is a co-ordinate bond?: A covalent bond in which both shared electrons come from one species, the ligand.
What is a complex?: A central metal atom or ion surrounded by ligands.
What is the co-ordination number?: The number of co-ordinate bonds to the central metal atom or ion.
What is the co-ordination number of [Cu(NH₃)₄(H₂O)₂]²⁺?: 6 (four NH₃ plus two H₂O).

Exam questions on General properties of transition metals

A student is comparing the electronic structures of some d-block elements. Iron has the configuration [Ar]3d⁶4s², scandium [Ar]3d¹4s², zinc [Ar]3d¹⁰4s² and copper [Ar]3d¹⁰4s¹.
Explain why zinc is not classified as a transition metal even though it is a d-block element.2 marks
Cobalt(II) chloride dissolves in water to give the pink complex ion [Co(H₂O)₆]²⁺. Adding excess ammonia solution forms [Co(NH₃)₆]²⁺, and adding concentrated hydrochloric acid forms the blue complex ion [CoCl₄]²⁻.
Ammonia, NH₃, can act as a ligand but the ammonium ion, NH₄⁺, cannot. Explain why.2 marks
Solid iron(II) sulfate dissolves in water to give a pale green solution containing [Fe(H₂O)₆]²⁺. On standing in air the solution slowly turns yellow-brown as iron(III) ions form. Finely divided iron is used as the catalyst in the Haber process.
Identify three characteristic properties of transition metals that are shown by the information, quoting the evidence for each.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).