Coordination Compounds: Naming, Geometry and Isomerism · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Naming complexes and spotting isomers

Science · Chemistry · ages 19-20
Name ______________________   Date ____________

  1. What is the coordination number of [Co(NH3)6]Cl3? Type the number.

    Answer: ______________

  2. What comes first when you name a coordination compound?

    • The metal with its oxidation state
    • The ligands in alphabetical order with their counts
    • The counter ions

  3. What is the oxidation state of cobalt in [Co(NH3)4Cl2]Cl? Type the number with its sign as a plain integer.

    Answer: ______________

  4. In a square planar complex, how do cis and trans isomers differ?

    • Cis puts matching ligands side by side and trans puts them opposite
    • Cis has more ligands than trans
    • Cis is always charged and trans is neutral

  5. What is the formula of hexaamminecobalt(III) chloride?

    • [Co(NH3)6]Cl3
    • [Co(NH3)3]Cl6
    • Co(NH3)6Cl

  6. In an octahedral complex, how do fac and mer isomers differ?

    • Fac covers one face and mer runs around the middle
    • Fac has three metals and mer has one
    • Fac is ionised and mer is neutral

  7. Three bidentate ligands around a metal give a coordination number of three.

    Circle one:   True   False

  8. Two complexes differ only in which atom of one ligand binds the metal. Which isomerism is this?

    • Coordination isomerism
    • Ionisation isomerism
    • Linkage isomerism
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Naming complexes and spotting isomers W1-mt_rkHM3jL3Ri-s1

  1. 6 · Six ammonias each donate one atom, so the count is six.
  2. The ligands in alphabetical order with their counts · Ligands lead, the metal follows, and the salt mates come last.
  3. 3 · The ligands sum to minus 3, so cobalt must be plus 3.
  4. Cis puts matching ligands side by side and trans puts them opposite · The two forms differ only in the relative positions of the matching pair.
  5. [Co(NH3)6]Cl3 · Hexa means six ammonias inside, and cobalt(III) needs three chlorides outside.
  6. Fac covers one face and mer runs around the middle · Three matching ligands can cap a triangular face or ring the equator.
  7. False · Each bidentate ligand donates two atoms, so three give six.
  8. Linkage isomerism · A swapped donor atom with everything else fixed means linkage isomerism.
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