complex ions transition metals can form complexes because their ions have a high charge density: o...
TRANSCRIPT
Complex ions• Transition metals can form complexes because
their ions have a high charge density: o they have quite a large nuclear charge but are relatively
small; o the 3d electrons are not so effective (as 2s or 2p
electrons) at shielding the effect of the ionic charge which really comes from the nucleus.
• This allows the transition metal ions to have a great polarising power and they can attract lone pairs from other atoms to form complexes.
Complex ions
• Ions formed by a metal ion to which a number of ligands (molecules and/or negative ions) are bonded using a dative bond
• Ligand = molecule or negative ion with a non-bonding pair of electrons which is used to make a dative bond
• Example: [Fe(H2O)6]3+ • Coordination number is the number of ligands
that surround the metal ion
More examples complex ions
[Fe(CN)6]3- [CuCl4]2-
[Cu(NH3)4]2+ [Ag(NH3)2]+
Charge on the ion is the sum of all charges.Work out the charge of each metal ion in the complexes above.
Naming complex ionsligand number
H2O - aqua 1 - monoOH- - hydroxo 2 - diNH3 - ammine 3 - triCl- - chloro 4 - tetraBr- - bromo 5 - pent CN- - cyano 6 – hex
You name the ligand and its number first before naming the metal. You use the name of the metal if the ion is positive but use –ate ending if negative e.g. ferrate, cuprate, vanadate.
Shapes complex ions
Depends on coordination number
• If 6 then shape = octahedral• If 4 then shape = tetrahedral (or square planar = less common)• If 2 then shape = linear
Shapes of complex ions
Coloured complex ions
Coloured Cu2+
Coloured ions
Factors affecting colour
• nuclear charge• oxidation state of ion (i.e. number of
electrons)• ligand• coordination number• shape of the complex
Colour complex ions