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Flashcards by umer.sabir, updated more than 1 year ago
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Created by umer.sabir
over 10 years ago
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| Question | Answer |
| What is a transition metal? | A d-block element that forms and ion with an incomplete d sub-shell |
| Why are scandium and zinc not classed as transition elements? | They don't have partially filled d sub-shells. |
| Which sub-shell is filled first and which sub-shell are electrons lost from first? | 4s sub-shell because it has a lower energy than 3d sub-shell |
| What are the properties of transition elements? | 1. Can form complex ions 2. They form coloured ions 3. They're good catalysts because they can change oxidation states by gaining or losing electrons. 4. They exist in variable oxidation states |
| What is a ligand? | A molecule or ion that can donate a pair of electrons to a metal ion to form a coordinate bond |
| What is a complex ion? | A transition element bonded to one or more ligands by coordinate bonds |
| What is the coordination number? | Indicates the number of coordinate bonds to the central metal ion |
| What is a monodentate ligand? | Can only donate one pair of electrons to a metal ion to form a coordinate bond |
| Examples of monodentate ligands | 1. Ammonia - NH3 (One lone pair on the nitrogen atom) 2. Chloride ions - :Cl 3. Water - Oxygen has 2 lone pairs of electrons but can only form one coordinate bond because the lone pairs are too close together. 4. Cyanide - :CN |
| What are bidentate ligands | Can donate 2 pairs of electrons to a metal ion to form two coordinate bonds |
| Example of a bidentate ligand | en (ethane-1,2-diamine) - is a bidentate ligand because it has 2 amine groups and each has a lone pair of electrons which they can donate to form coordinate bonds |
| What are multidentate ligands? | Can donate more than one pair of electrons to form coordinate bonds with the metal ion |
| Example of a multidentate ligand | 1. EDTA4- (2 lone pairs on nitrogen atoms and 4 lone pairs on oxygen atoms) can form 6 coordinate bonds with central metal ion. |
| What is the shape and bond angle of a complex ion with a coordination number of 6? | Shape - Octahedral Bond angles - 90° |
| What is the shape and bond angle of a complex ion with a coordination number of 4? | Shape - Tetrahedral Bond angles - 109.5° |
| Some complexes show a square planar shape, name one example and the bond angles | Cis-platin Bond angles - 90° |
| Optical isomers only form when... | Carbon atom is attached to different atoms or groups of atoms |
| What are optical isomers also known as? | Enantiomers |
| What is cis-platin used for? | 1. Used to treat cancer 2. Prevents cancer cells from reproducing 3. Cis-platin binds to DNA and stops DNA from unwinding so DNA can't replicate |
| What is ligand substitution? | When one ligand in a complex ion is replaced by another |
| [Co(H2O)6]2+(aq) + 6NH3(aq) ==> | [Co(NH3)6]2+(aq) + 6H2O(l) |
| [Cr(H2O)6]3+(aq) + 6OH–(aq) ==> | [Cr(OH)6]3–(aq) + 6H2O(l) |
| [Cu(H2O)6]2+(aq) + 4Cl–(aq) ==> | [CuCl4]2–(aq) + 6H2O(l) |
| [Co(H2O)6]2+(aq) + 4Cl–(aq) ==> | [CoCl4]2–(aq) + 6H2O(l) |
| [Cu(H2O)6]2+(aq) + 4NH3(aq) ==> | [Cu(NH3)4(H2O)2]2+(aq) + 4H2O(l) |
| What is the function of haemoglobin? | Transports oxygen around the body |
| What metal ion can oxygen bind to in haemoglobin? | Fe2+ |
| What ligand is replaced by oxygen? | H2O is replaced by oxygen in the lungs |
| How does carbon monoxide bind to Fe? | 1. Instead of water being substituted for oxygen it is substituted for carbon monoxide 2. Carbon monoxide binds more strongly than oxygen, this reaction is irreversible 3. This makes the Hb useless 4. Carbon monoxide causes organs to starve of oxygen |
| Why is water not included in stability constant equations? | Because it is in large excess and is virtually constant |
| How to write a stability constant | [Products] ------------------------------ [Reactants] |
| What does a large value of Kstab indicate? | 1. Position of equilibrium lies to the RHS. 2. Complex ion is stable and can be easily formed. |
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