General Physical & Chemical Properties of the First Row of Transition Elements, Titanium to Copper (Cambridge (CIE) A Level Chemistry): Flashcards
Exam code: 9701
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Define transition element.
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Define transition element.
A transition element is a d-block element that forms one or more stable ions with an incomplete d subshell.
True or False?
Scandium is classified as a transition element.
False. Scandium is not a transition element because its only stable ion, Sc3+, has no electrons in the 3d subshell — giving it the electronic configuration of [Ar].
Why is zinc not classified as a transition element?
Zinc forms only one ion, Zn2+, which has a complete 3d subshell with the electronic configuration [Ar]3d10. Transition elements must form at least one ion with an incomplete d subshell.
The 3dxy orbital has .......... lobes that point .......... the x and y axes.
The 3dxy orbital has four lobes that point between the x and y axes.
Define 3dz2 orbital.
A 3dz2 orbital is a d orbital with two main lobes pointing along the z-axis and a doughnut-shaped ring of electron density around the centre.
List four characteristic properties of transition elements.
Transition elements have: variable oxidation states, act as catalysts, form complex ions and form coloured compounds.
True or False?
Iron can form ions with oxidation states of +2 and +3.
True. Iron forms Fe2+ (Fe(II)) and Fe3+ (Fe(III)) ions, illustrating the variable oxidation states typical of transition elements.
Transition elements are found in the .......... block of the Periodic Table, between Groups .......... and .......... .
Transition elements are found in the d block of the Periodic Table, between Groups 2 and 13.
What are the common oxidation states of vanadium?
Vanadium commonly exhibits oxidation states of +2, +3, +4 and +5.
Why can transition elements have variable oxidation states?
The 3d and 4s subshells are similar in energy, so a similar amount of energy is needed to remove different numbers of electrons. This allows transition elements to form ions by losing varying numbers of electrons.
Define autocatalysis.
Autocatalysis is a process in which a reaction is catalysed by one of its own products as it forms, causing the reaction to speed up progressively.
True or False?
When transition elements form ions, the 4s electrons are lost before the 3d electrons.
True. When transition elements form ions, the 4s subshell electrons are removed first, followed by electrons from the 3d subshell.
The most common oxidation state of transition metals is .........., formed when the .......... electrons are lost.
The most common oxidation state of transition metals is +2, formed when the 4s electrons are lost.
Give the electronic configuration of Ti3+.
Ti3+ has the configuration 1s2 2s2 2p6 3s2 3p6 3d1. Two 4s electrons and one 3d electron are removed from the titanium atom.
True or False?
Transition elements act as catalysts because they have vacant d orbitals that can accept lone pairs from ligands.
True. The energetically accessible vacant d orbitals allow ligands to donate lone pairs via dative bonds, enabling transition element ions to act as catalysts.
Define complex ion.
A complex ion is a charged species consisting of a central metal atom or ion surrounded by one or more ligands, which donate lone pairs to form dative covalent bonds.
Why do higher oxidation states become less stable towards the end of the 3d transition series?
As nuclear charge increases across the d block, the 3d electrons are attracted more strongly to the nucleus and become harder to remove. Higher oxidation states are therefore less stable and elements are more likely to retain their 3d electrons.
In a catalytic cycle, Fe2+ acts as a reducing agent by losing an electron to form .......... , which can then act as an .......... agent.
In a catalytic cycle, Fe2+ acts as a reducing agent by losing an electron to form Fe3+, which can then act as an oxidising agent.
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