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50 Cards in this Set
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- 3rd side (hint)
Definition of a transition metal |
Is a d-block element that has an incomplete d-subshell as a stable ion
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What two metals are not classed as transition metals and why? |
Scandium- forms only sc3+ ion, in which the d orbitals are empty Zinc- only form zn2+ ion, in which the d-orbitals are full |
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What two transition metals do not follow the regular electron pattern and why? |
Chromium- the five 3d orbitals and the 4s orbital all contain one electron, with no obital being filled Copper- the five 3d orbitals are full, but there is only one electron in the 4s orbital |
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Why do transiton metals lose electrons from their 4s orbital before 3d? |
The 3d and 4s energy levels are very close together and, once electrons occupy the orbitals, the 4s electrons have a higher energy and are lost first |
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Physical properties of transition metals? |
-lustrous in appearance -high density -high melting and boiling point -when solid exist as giant metallic lattices, containing delocalised electrons, which move freely to conduct electricity |
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Chemical properties of transition metals |
-have different oxidation states -form coloured compounds when dissolved in water -catalyse chemical reactions |
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What colour is potassium dictomate and what is it used for? |
Orange crysallime solid Acts as an oxidising agent in preparation of aldehydes and ketones from alcohols |
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What is disproportionation reaction? |
Both species oxidised and reduced in the same chemical reaction Eg. Copper oxide is reacted with hot dilute sulfuric acid , a brown precipitate of copper and blue solution of copper sulfate are formed |
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How do transition metals obtain their colour? |
When white light passes through the solution, some of wavelengths of visible light are absorbed. The folour that we observe is a mixture of the wavelengths of the light that have not been absorbed. Eg. Copper sulfate appears pale blue, because the solution absords red/orange but reflects blue |
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How do transition metals work as catalysts? |
1) provide a surface on which the reaction can take place. Reactants ae absorbed onto the surface of the metal and held in place while the reaction occurs. Afte the reaction, the products are deabsorbed and the metal remains unchanged.
2) transition metals can change oxidation state by gaining and losing electrons. They bind to the reactants, formijg intermediates as part of a chemical pathway, ofter with a lowet activation energy, which speed up the reaction |
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Advantages and disadvantages of using transition metals in industry |
Advantages: inprove profits by reducing time it takes to make the product and reduce the amount if energy needed to make the reaction occur Disadvantage: can be toxic. When substances bring to the active site and stop the transition metals from working, the catalyst can no longer be used. It must be disposed of in a way not to cause harm or pollution. |
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Examples of transition metal catalysts in industry? |
Haber process: iron catalyst Contact process: vandium oxide catalyst Hydrogenation of alkenes: nickel catalyst Decompositon of hydrogen peroxide manganese oxide Hydrogen production: coppersulfate catalyst |
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Definition of complex ion |
A transition metal ion bonded to one or more ligands by coordinate bonds |
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Definition of ligand |
A molecule or ion that can donate a lone pair of electrons to the transition metal ion to form a coordinate bond |
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Coordination number |
Is the total number of coordinste bonds formed between a central metal ion and its ligands |
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What are Monodentate ligand and examples |
Ligand only donates just one pair of electrons to the central metal ion to form one coordinate bond |
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What are bidentate ligands? And example |
Have two pair of electrons from different atoms to donate to the central metal. This means two coordinate bonds can be formed. Eg. NH3CH2CH2NH2 'en' |
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What is a hexadentate ligand? And example- what is its purpose |
Hexadentate ligands has 6 lone pairs of electrons available to form coordinate bonds. Eg EDTA^ 4- EDTA is used to bind metal iond and is known as a chelating agent. This means it decreases the concentration of the metal ions in solutions by binding them into the complex. |
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What are 6 fold coordination called? What do they look like? Angles? |
Octahedral. All bond angles as 90 or 180 degree. Coordination number is 6 |
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Four-fold coordination shapes? And details of them |
Tetrahedral- chlorine ligands are so large that only four can fit around a transition metal Square planar- eg cis platin |
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Definition of stereoisomer? |
Species with the same structural formula but with a different arrangement of the atoms in soace |
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What two isomers did alfred werner discover? What colour were they? |
(Co(NH3)4Cl2) Cis-purple Trans-green |
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Isomerism in four coordinate complex? Example? |
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How is transition metal complexes used in medicine? Eg cis platin |
Cis platin is used as treatment ( chemotherapy) for cancer. Cells divide to make more cells of the same type. Cancer is spread through an organism by cell division of cancerous cell that can reproduce itself Cis-platin binds to the DNA of fast growing cancer cells. This prevents cell division. Activation of the cells repair mechanism eventually leads to the death of the cancer comtaining cell. But carboplatin as been developed- used for ovarian cancer. Lower dose and fewer side effects. |
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Structure of bidentate ligand- ethanedioate ligand |
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Cis- trans isomers of 2 monodentate and 2 bidentate ligands |
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What are optical isomers and examples? |
Optical isomers are non- superimpossible mirror images of each other Requirements: - 3 bidentate ligands (Ni(en)3)2+ -2 bidentate and 2 monodentate (co(en)2Cl2) -one hexadentate ligand eg (cu(EDTA))2- |
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Definition of ligand substitution |
Is a reaction in which one ligand in a complex ion is replaced by another ligand |
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Colour change and equation for aqueous copper (ii) ions and ammonia |
Small amount of ammonia: Pale blue --> pale blue precipitate formed Excess ammonia --> pale blue precipitare dissolve and deep blue solution forms. |
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Copper (ii) ions and hydrochloric acid equation and colour change |
Concentrate hydrochloric acid is added to aqueous copper ions: Pale blue --> yellow --> green Can be reversed by adding water |
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Why do complexes only fit 4 chlorine ligands |
Chlorine ions are larger than water ligands and have stronger replusions, so fewer chlorine ligands can fit around the central metal ion. Has a tetrahedral shape. |
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Products/ colour and equation of the reaction of chromium (iii) and ammonia |
Dark green--> green precipitate When a small amount of ammonia is added hydrogen ions are pulled off the water ligands. When excess ( concentrated) ammonia is added, some of the green precipitate re-dissolves to form a dark green solution. All ligands are replaced by ammonia |
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Role of haemoglobin |
Contains iron haem group Oxygen can bind to this. As blood passes theough the lungs, the haemoglobin picks up oxygen and carries itto every living cell, where it can be released. |
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Structure of haemoglobin and its bonding |
4 coordinate bonds between Fe2+ and nitrogen One bond between globin and fe2+ One bond between oxygen and fe2+ |
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Carbon monoxide as an example for ligand substitution in haemoglobin And symptoms |
Leaves fewer haemoglobin molecules to bind to oxygen molecules. Tissues can be starved of oxygen. Reaction is not reversible. Symptoms include headaches nausea and pottential suffocation. Can be fatal. |
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When is carbon monoxide formed? How can we detect it? |
Incomplete combustion of carbon containing fuels. Burning tobacco- why smokes become short of breath Its odourless and colourless Sensors like smoke detectors. |
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Colour change and equation: Cu2+ and NaOH/ NH3 |
NaOH: blue to blue gelatinous precipitate NH3: blue to blue geletinous precipitate which redissolves to blue solution |
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Colour change and equation of Fe2+ and NaOH/NH3 |
Naoh: pale green to green precipitate tunring rusty brown at its surface standing in air Nh3: pale green to dark green precipitate |
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Colour change and reaction of Fe3+ and naoh / nh3 |
Naoh: pale yellow to rust brown precipitate
Nh3: pale yellow to rusty brown precipitate
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Colour change and equation mn2+ and nh3/naoh |
Naoh: pale pink to brown precipitate that darkens in the air as it oxidises Nh3: brown precipitate |
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Colour change and reaction of cr3+ and naoh/ nh3 |
Naoh: green to green precipitate Nh3: green precipitate which redissolves if excess ammonia is added |
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What does a redox reaction involve? |
The transfer of electrons from one species to another Oxidising agent can be titratwd against reducing agent |
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How does a titration involving manganate ions work? |
Used to oxidise Fe2+ ions. The solution is acidified with sulfuric acid. Hcl cannot be used as it reacts with mno4-. It is unsafe because chlorine gas is formed. Mn04 is in th3 burette. Iron 2+ in the connical flask eith sulfuric acid |
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Pottasium dicromate and Fe2+ ions colour and equation |
Colour change is very subtle. Indicator is used which produces a violent- blue coloured point |
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Iodine ane thiosulfate equation and reaction |
Forms tetrathionate ion
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Copper and iodine titration colour change and reaction and then titrated against sodium thiosulfate |
Poduces light brown/ yellow solution and white precipitate of copper iodide When titrated agains sodium thiosulfate , becomes paler. Starch is added as a indicator. |
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Positive ions- testing for ammonia ions |
Ammonia ion reacted eith hydroxide ions. Add sodium hydroxide and warm gently. Distinctive smell gass turns red litmus paper blue. |
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Negative ions- testing for carbonate ions |
Add stong acid eg hcl Collect any bubbles or gas and pass through limewater. Limewater turns cloudy. |
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Negative ions- testing for sulfate ions |
Add dilute hydrochloric acid barium chloride. White precipitate is formed. |
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Negative ions- testing for halide ions |
Dissolve suspected halide in water if not in aqueous form Add dilute nitric acid and aqueous silver nitrate Chloride ions- white precipitate Soluble in dilute nh3 Bromide ions- cream precipitate Soluble in concentrated nh3 Iodide ions- yellow precipitate Insoluble in both nh3 |
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