Transition Metals

Madeleine.Dc
Flashcards by Madeleine.Dc, updated more than 1 year ago
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OCR A2 Chemistry - F325, Transition Elements

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Question Answer
What are transition metals? A d-block element that forms an ion with an incomplete d sub-shell.
Why are scandium and zinc not transition metals? Scandium has a completely empty sub shell and zinc has a completely full d sub shell. The d sub shell must be incomplete for it to be a transition metal.
How do you write electron configurations for elements and ions? mads.png (image/png)
Why do chromium and copper not follow the electron configuration pattern? Electron repulsion in the outer electrons are minimised resulting in increased stability of the atoms.
What is the electron configuration of chromium? 1s2 2s2 2p6 3s2 3p6 4s2 3d5
What is the electron configuration of copper? 1s2 2s2 2p6 3s2 3p6 4s1 3d10
What happens to a transition element in a reaction? They lose electrons to form positive ions; losing their 4s electrons before their 3d electrons.
Why are 4s electrons lost first? They have a higher energy.
What is the difference between a d block element and a transition element? Transition elements are elements where the d orbital is incomplete whereas d block elements have a d orbital as the highest energy and this can be empty or full.
Write the electron configuration for: Cr, Mn2+, Sc3+ and Ti 1s2 2s2 2p6 3s2 3p6 4s2 3d5 1s2 2s2 2p6 3s2 3p6 3d5 1s2 2s2 2p6 3s2 3p6 1s2 2s2 2p6 3s2 3p6 4s2 3d2
Physical properties of transition metals. Shiny in appearance High densities High melting points High boiling points
What do transition metals exist as when they are solids? Giant metallic lattices, containing delocalsised electrons which can move to conduct electricity.
Uses of transition metals Coins Joint replacements Telephone boxes Alloyed for use in construction
Transition elements from titanium to copper can form ions with how many oxidation states? Two or more
Why do transition metals form compounds with ions in the +2 oxidation state? As they lose the 2 electrons from the 4s orbital. (Higher energy level than that of 3d orbital, although close together)
Why are compounds containing transition metal ions coloured? Some of the wavelengths of visible light are absorbed. The colour is a combination of the wavelengths that have not be absorbed.
What is a catalyst? A substance that increases the rate of a reaction by providing an alternative route with a lower activation energy.
Why are transition metals good catalysts? They provide a surface on which a reaction can take place. Transition metal ions have the ability to change oxidation states by gaining or losing electrons. They then bind to reactants forming intermediates as part of a chemical pathway with a lower activation energy.
Haber Process N2(g) + 3H2(g) <=> 2NH3(g) Iron metal is the catalyst
Contact Process 2 SO2(g) + O2(g) ⇌ 2 SO3(g) Vandium Oxide catalyst, V2O5 - V has the 5+ oxidation state
Hydrogenation of Alkenes Unsaturated compounds to saturated compounds. Nickel catalyst, lowers the temperature and pressure.
Decomposition of hydrogen peroxide. 2H2O2 ---> 2H20 + O2 Manganese oxide is the catalyst with +4 oxidation state.
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