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28 Cards in this Set
- Front
- Back
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What's a transition metal? |
A transition metal has one or more unpaired d-electrons in one of its ions |
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Which two of the d block elements aren't transition metals? |
Scandium (which only has Sc3+) as it's ion. This has no d electrons so it's not a TM. Zinc doesn't form a Zn3+ ion. It forms a Zn2+ ion which has all of its d shell filled and paired. |
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What's the period 3 trend in first ionisation? |
There's a general upward trend from sodium to argon. This is due to the increase in nuclear charge without an increase in the number of shielding in the inner orbitals. The nuclear charge increases considerably. That's why there's an upward trend in period 3 |
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What are the properties of TM? (In terms of oxidation) |
They have more than one oxidation state. Non TM d - block elements such as scandium and since only have 1 oxidation state. |
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What are the chemical properties of TM in terms of bonding? |
The most of the TM with oxidation states of 2+ and 3+ bond ionically. Anhydrous halides bond covalently but are ionic when hydrated. When the oxidation is above 4+ it gets covalently bonded often in an anion. |
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Why do d block ions become hydrated when dissolved in water? |
The oxygen atom in water has a lone pair of electrons that forms a bond with the empty 3d or 4p orbital in the metal ion. A dative covalent bond forms with the oxygen as the donor. |
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What is the coordination number? |
It's the number of neighbouring atoms that are bonded to the central ion. |
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What molecules/anions can form complex ions with TM cations? What are these examples of? |
Ammonia and organic amines- (the Nitrogen as the lone pair)
Anions such as Cl- and CN- These are examples of MONODENTATE LIGANDS |
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Why can you only fit 4 chloride ions around a small cation such as Cr3+? |
It's energetically unfavourable. The Cl- is much larger than the small cation. |
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What shape is the CuCl2 complex ion? |
It's linear with 180 degree shape. |
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What shape is cisplatin? |
It's planar. |
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How are Bi - dentate ligands different to MONODENTATE ligands? |
It has more than 1 lone pair of electrons in different places and can form 2 dative covalent bonds. |
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What is a heterogenous catalyst? |
A heterogenous catalyst is in a different phase from the reactants e.g iron solid catalyst in the born haber process. |
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How do heterogenous catalysts work? |
1) the gaseous reactants bind to the active site on the catalyst and so the reactants get adsorbed. 2) the adsorbed reactants react and form the adsorbed product 3) the products are released and the active site is emptied for more gaseous reactants. |
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How can TM act as a catalyst? |
It can act as a catalyst because it's energetically available d - orbitals can accept electrons from a reactant molecule or its d electrons can form a bond with a reactant molecule. |
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What are homogenous catalysts? |
Homogenous catalysts are in the same state as the reactants. They always work via an intermediate compound/ion. They end up getting re generated at the end. |
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What's a d-d transition? |
When white light shines through a solution of a complex ion of a transition metal, photons of a particlar energy are absorbed and their en every promotes an electron from the lower energy level to the upper energy level.
This is called the d-d transition.
The solution has the complementary colour to the light absorbed. The electron drops back down and energy is released as Heat. |
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Which elements can't undergo d-d transition? |
Zinc, scandium and copper 1 so they form white compounds. |
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What happens when a base is added to a solution of hydrated d block ions? |
Deprotonation takes place depending on the strength of the base. |
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What is deprotonation? |
Deprotonation is the reaction in which the base removes a H+ ion from the species. |
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What kind of base is water? What does it deprotonate? What kind of solution does it form? |
It's a weak base and it deprotonates 3+ aqua ions e.g [Cr (H2O)6]3+ It's not extensive. It's reversible. [Cr(H2O)5(OH)]2+ and H3O+
Acidic as H3O+ is formed. |
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When is an insoluble species from in deprotonation? |
When a strong bases are added. It's an irreversible reaction.
It produces a neutral precipitate and so it deprotonates until the charge on the compound goes.
With OH-, the product formed is the precipitate and water
With the NH3 ligand, NH4+ is formed. |
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What are the colours of the precipitates of Cr3+ , Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+? what happens if the react with excess NaOH |
Cr3+ green from green solution
Mn2+ off white
Fe2+ green
Fe3+ red brown
Co2+ blue
Ni2+ green
Cu2+ blue
Zn2+ white forms a colourless solution |
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What happens when you add excess ammonia? What precipitates for they form - Cr3+ , Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+? |
Ligand exchange occurs.
Cr3+ , green ppt dissolves slightly to form green solution Mn2+, off white ppt remaims Fe2+, green ppt remains Fe3+, red brown ppt remains Co2+, blue ppt dissolves to form brown solution Ni2+, green ppt dissolves to form pale blue solution Cu2+, blue solution dissolves to form a deep blue solution Zn2+, White precipitate dissolves to form a colourless solution.
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Why are the stability constants of bi and ploy dentate ligands high? |
It's because of the entropy changes in the system. The number of particles increase and so does the arrangement - delta A system increases. |
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How is feasibility of a redox reaction indicated in terms of Ecell as in how do you work it out? |
You reverse the half equation with the reactants on the right hands side (what's being reduced) |
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What's titanium used for? |
Forms a protective oxide layer and does not corrode even at high temperatures. It has high strength to white ratio and is used in aeroplanes and bikes. It's expensive as it's difficult to wels |
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What's chromium used for? |
It's also forms a protective oxide layer like titanium BUT it's doesn't have a good strength to ratio like titanium. It's used as to make the alloy- stainless steel. |
