Chemistry A2 Level

• a d-block element that have atleast one stable ion with an incomplete d sub-shell
• Element Ti-Cu

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• variable oxidation states: arises from the similar energies required for removal of 4s and 3d electrons
• coloured ions: a full or empty d sub-shell ions are colourless, coloured ions are foormed by the ease of transition of electrons between energy level, energy is absorbed when an electron is promoted to a higher level, the frequency of light is proportional to the energy difference
• catalytic behaviour: partly filled d-orbitals can be used to form bonds with adsorbed reactants

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• Copper (II): pale blue solution to a blue precipitate
• Cobalt (II): pink solution to a blue precipitate, turns beige in the presence of air
• Iron (II): pale green solution to a green precipitate, turning rusty brown at its surface on standing in air
• Iron (III): pale yellow solution to rusty brown precipitate

a molecule or ion that cn donate a pair of electrons with the transition metal ion to form a coordinate bond

a transition metal ion bonded to one or more ligands by coordinate bonds

the total number of coordinate bonds formed between a central metal ion and its ligands

• six coordinate bonds
• 90^o bond
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• the ligand can donate two lone pairs of electrons to the central metal ion to form two coordinate bonds
• common bidentate ligand: ethane-1,2-diamine, NH₂CH₂CH₂NH₂, often shortened to 'en'
• form octahedral complexes
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an anti-cancer drug and its action by binding to DNA in cancer cells, preventing division

• contains iron, Fe2+ ions, which form 6 coordinate bonds
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• if the oxygen concentration is high a water molecule is substituted for an oxygen molecule, forming oxyhaemoglobin and is transported around the body where it is exchanged for a water molecule again
• if CO is in the system the water molecule is swaped with CO, forming carboxyhaemoglobin. the CO is a strong ligand so it cannot be exchane with oxygen or water. the haemoglobin cannat transport oxygen anymore

• K_stab
• the equilibrium constant for the formation of a complex ion in a solvent from its constituent ions
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• a large stability constant means the complex ion is very stable