OCR A - A Level Chemistry - Transition elements

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Silxnt1
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As all you chemists know, transition elements can exist in variable oxidation states as ions. Unsurprisingly, there are so many of these; of which most are coloured.

If anyone knows, for the OCR A - A Level Chemistry specification, is it a requirement to memorise all of the ions AND their colours for every transition element in the first row of the d-block?

I've checked the specification and nothing seems to be explictly clarified, here's an extract:
"(c) illustration, using at least two transition
elements, of:
(i) the existence of more than one oxidation
state for each element in its compounds
(see also 5.3.1 k)
(ii) the formation of coloured ions (see also
5.3.1 h, j–k)
(iii) the catalytic behaviour of the elements and
their compounds and their importance in
the manufacture of chemicals by industry
(see 3.2.2 d)
No detail of how colour arises required.
Practical examples of catalytic behaviour include:
Cu2+ for reaction of Zn with acids;
MnO2 for decomposition of H2O2.
No detail of catalytic processes required.
HSW9 Benefits of reduced energy usage; risks from
toxicity of many transition metals."

It seems like way too much to memorise, but I want to be sure that it's what's required to be done for the specifcation before I waste a lot of time trying to memorise them all
Last edited by Silxnt1; 4 months ago
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Pigster
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You are completely mis-reading the spec.
(i) just states that TEs can have more than one o.n.
(ii) states that they can have colours
(iii) TEs and their ions can be catalysts - there are plenty mentioned in other parts of the spec. e.g. Ni for hydrogenation, Fe for Cl2 + benzene

Later in the spec. there are stated colours you're expected to know e.g. ppt of TE using OH- etc which therefore have crossover with (i) and (ii)


To be clear, you aren't expected to know all of the o.n. and all of the colours.
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Silxnt1
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(Original post by Pigster)
You are completely mis-reading the spec.
(i) just states that TEs can have more than one o.n.
(ii) states that they can have colours
(iii) TEs and their ions can be catalysts - there are plenty mentioned in other parts of the spec. e.g. Ni for hydrogenation, Fe for Cl2 + benzene

Later in the spec. there are stated colours you're expected to know e.g. ppt of TE using OH- etc which therefore have crossover with (i) and (ii)


To be clear, you aren't expected to know all of the o.n. and all of the colours.
I did not say that the specification was the reason I believed it might be the case that I would have to memorise them all. I simply provided an extract from it to assist anyone reading the article in helping me deduce what is needed to be learnt with regards to the initial query, therefore I am not 'completely mis-reading the spec'.

Also, I didn't quite get that second-to-last part of what you said. What am I expected to know with regards to the inital query
Last edited by Silxnt1; 4 months ago
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Pigster
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(Original post by Silxnt1)
Also, I didn't quite get that second-to-last part of what you said. What am I expected to know with regards to the inital query
The important lines of the TE spec are:

Learners should be able to demonstrate and apply their knowledge and understanding of:
(j) reactions, including ionic equations, and the accompanying colour changes of aqueous Cu2+, Fe2+, Fe3+, Mn2+ and Cr3+ with aqueous sodium hydroxide and aqueous ammonia, including:
(i) precipitation reactions
(ii) complex formation with excess aqueous sodium hydroxide and aqueous ammonia

(h) ligand substitution reactions and the accompanying colour changes in the formation of
(i) … [CuCl4]2– from [Cu(H2O)6]2+
(k) redox reactions and accompanying colour changes for:
(i) interconversions between Fe2+ and Fe3+
(ii) interconversions between Cr3+ and Cr2O72–
(iii) reduction of Cu2+ to Cu+ and disproportionation of Cu+ to Cu2+ and Cu
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