Transition metals
Transitionmetalsareelementswith an incomplete d subshell that canform
at least onestableion with an incomplete d subshell
thisdefinitiondistinguishesthemfromd blockelements asSc and 2n
Sc full setof d electrons
I Sc 4414111
onlyforms
Infinity an has a
not a transitionmetal
Chromium andcopper are an
exceptions
Co 1s 25 2ps 35 3p 3 4s
I Cr 1s 25 2 35 3 3d 45
p p
This is becausetheseconfigurations are more energetically
stable an electron is promoted
GeneralProperties variable oxidationstates
Variableoxidationstates form ve ions
Formscomplexions Romannumerals are usedto
Formcoloured compounds indicate the oxidationstateon the
Behave as catalysts metalion
Eg Felt Fe Il
Transitionelements as catalysts
forming coloured compounds
theycanmakeexcellentcatalysts Cr OH darkgreen as
duringcatalysistheycanchange to Cr'tis darkgreen
various oxidationstatesbygaining Cr NH purpleas Cr'tis
donatingelectrons purple
Aheterogenouscatalyst is in a
differentphysicalstate phase from thereactants
reaction occurs at activesiteson thesurface of the catalyst
A homogeneouscatalystis in thesamephysicalstate phase as thereactants
, forming complexions
a moleculelion consisting of a centralmetalatomlion witha numberof
moleculeslionssurrounding it
co ordinatebondbydonating a pairofelectronstothebond electronpairdonor
Dueto differentoxidationstatesofcentralmetalions a differentnumberandwide
varietyofligandscanformbondswiththetransitionelement
beingdonated nucleophile
Differentligands can form differentnumbers ofdativebondstothecentralmetalion
in a complex
some ligandscan form 1 dativebond
otherligandscanform 2 multipledativebonds
CO ordinationnumber number ofco ordinatebondsto thecentralmetalatom
lion
Monodentateligands
can formonlyonedativebondto thecentralmetalion
H2Omolecules NH3molecules
Hi
I
I 6
NH3
Bidentateligands
can form2 dativebondsto centralmetalion eachligand atomswithLPs
contains
1.2 diaminoethaneCen Colen
1