module 5: murphy, transition metals Flashcards
what is a transition metal
a metal that forms at least 1 ion that has a partly filled d sub-shell
from Ti to Cu
not Sc or Zn
what are some properties of transition metals
- Variable oxidation states
- Form complex ions
- Form coloured compounds
- Behave as catalysts
- high density, melting point and boiling point
- good electrical conductors
give examples of transition metals as catalysts
iron - haber process
nickel - hydrogenation of C=C
vanadium pentoxide - contact process
what is a complex ion
a complex ion has ligands bonded to a central positive ion through dative covalent bonds
what is a ligand
an ion or a molecule that can form dative covalent bonds to a positive transition metal ion by donating an electron pair
so, they have a negative charge/lone pair of electrons capable of being donated, bc a ligand is a nucleophile
what is a monodentate ligand, with examples
a ligand that can form only 1 dative bond to the central metal ion
eg. H2O, NH3, Cl-
what is a bidentate ligand, with examples
a ligand that can form 2 dative bonds to the central metal ion, because each ligand has 2 atoms with a lone pair of electrons each
eg. 1,2-diaminoethane (NH2CH2CH2NH2)
what is a six-coordinate complex
an octahedral complex, formed when a central metal atom/ion forms 6 coordinate bonds
could be 6 with mono dentate ligands or 3 with bidentate ligands
what is a four-coordinate complex and what ligands can they be found with
when four coordinate bonds form with the central metal ion/atom, usually tetrahedral, sometimes square planar
tetrahedral - most common with 4 chloride ions as they are large, allowing only 4 to fit
square planar - most common with cyanide ions, found in cisplatin
can transition element complexes exhibit stereoisomerism?
yes, square-planar and octahedral complexes with two ligand pairs exhibit cis-trans isomerism
this is geometric isomerism
can transition metal complexes exhibit optical isomerism and what is it
octahedral complexes with bidentate ligands have optical isomers
the two forms are non-superimposable images of each other, they have no plane of symmetry and one image can’t be placed directly on the other
what is cis-platin
a cancer treatment drug
it passes through the cell membrane and undergoes ligand exchange, binding to nitrogen atoms on the bases in DNA
this distorts the DNA’s shape and prevents its replication
adverse effects:
- binds to healthy and cancerous cells, so other cells that replicate quickly eg. hair follicles are also affected
what is assumed when a transition element ion is in solution
assumed that it exists as a hexaaqua complex ion (i.e. it has six water ligands attached to it)
what is the ionic equation and colour change when NaOH or aqueous ammonia is added dropwise to Cu(II) in solution
what is the ionic equation and colour change when excess concentrated ammonia is added to the product
- partial ligand substitution of 2 water ligands by 2 hydroxide ligands
- another partial ligand subsitution
what is the ionic equation and colour change when NaOH or aqueous ammonia is added dropwise to Fe(II) in solution
what is the ionic equation and colour change when excess conc. ammonia is added to the product
no change with excess conc.
dark green ppt not pale green
what is the ionic equation and colour change when NaOH or aqueous ammonia is added dropwise to Fe(III) in solution
what is the ionic equation and colour change when excess conc. ammonia is added to the product
no change with excess conc
what is the ionic equation and colour change when NaOH or aqueous ammonia is added dropwise to Cr(III) in solution
what is the ionic equation and colour change when excess NaOH/aqueous ammonia is added to the product
with excess OH: green solution [Cr(OH)6]^3-
with excess NH3: purple solution [Cr(NH3)6]3+
what is the ionic equation and colour change when NaOH or aqueous ammonia is added dropwise to Mn(II) in solution
what is the ionic equation and colour change when excess concentrated ammonia is added to the product
no change with conc ammonia