Chemistry A2 Level

Card Set Information

Chemistry A2 Level
2012-01-02 14:58:23
chemistry alevel transition elements

Transition Elements
Show Answers:

  1. Electron configurations
  2. Transition elements
    • a d-block element that have atleast one stable ion with an incomplete d sub-shell
    • Element Ti-Cu
  3. Properties
    • 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
  4. Precipitation reactions
    • 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
  5. Ligand
    a molecule or ion that cn donate a pair of electrons with the transition metal ion to form a coordinate bond
  6. Complex ion
    a transition metal ion bonded to one or more ligands by coordinate bonds
  7. Coordination number
    the total number of coordinate bonds formed between a central metal ion and its ligands
  8. Complexes with sixfold coordination with an octahedral shape
    • six coordinate bonds
    • 90o bond
  9. Bidentate ligand
    • 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
  10. Stereoisomerism: cis-trans
  11. Stereoisomerism: optical
  12. cis-platin
    an anti-cancer drug and its action by binding to DNA in cancer cells, preventing division
  13. Ligand substitution
  14. Haemoglobin
    • contains iron, Fe2+ ions, which form 6 coordinate bonds
    • 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
  15. Stability constant
    • Kstab
    • the equilibrium constant for the formation of a complex ion in a solvent from its constituent ions
    • a large stability constant means the complex ion is very stable
  16. Redox reactions