Transitional Metals Flashcards
Transitional Metals
metal that can form one or more stable ions with incomplete d sub-level
- all ele in period 4 block elements = transitional metal except scandium and zinc
- transitional metal must have at least 1 to 9 ele in d subshell
electron configurations
4s = lower eng than 3d
- fill 4s then 3d
exception of electron configuration
- chromium prefers one ele ion each orbi of 3d sublevel and just one in 4s = give more stability
- copper prefers full 3d level and just one ele in 4s level - more stability
Transition metal ions
transition metal = form positive ions
- 4s electron removed first then 3d electrons
Scandium
- only forms one ion, Sc3+ = has empty d sublevels
- not transitional metal
[Ar]3d1 4s2
Zinc
- only form one stable ion, Zn2+
- has full d sublevel
- when ion formed closed 2 ele, both form 4s sub level = keeps full 3d sub level
Physical properties
- high density
- high melting and high boiling points
chemical properties
- can form complex ions
- form coloured ions
- are good catalyst
- exist in variable oxidative states
incomplete d sublevels
- incomplete d sub level that causes special chem prop of trans metal
- d block ele without incomplete d sub level don’t have these prop
Complex ions
metal ion surrounded by co-ordinately bonded ligands
Co-ordinate bond
- or dative covalent bond
- is cova bond in which both ele in the shared pair come from same atom
ligand
an atom , ion or mole that donates pair of ele to central metal ion
- must have at least one lone pair of electronsc
monodentate
ligands that can only form one type of co-ordinate bond
- ammonia ion
- chloride ion
- water - has 2 lone pairs but cuz they are close toge - can only form one co-ordinate bond at time
Multidentate
- ligand that can form more than one co-ordinate bond
- EDTA 4- has 6 lone pairs ( 2 on N and 4 on O2 )
- multidentate ligand that can only form 2 bonds = bidentate
ethane-1,2-diamine
Oxidation state of metals in complex ions
oxidation state = total charge of complex - sum of charges of ligands
Shapes of complex ions
- shape - depends on it’s co-ordinate number
- usual co-ordinate numbers are 6 and 4
- if ligand small ( H2O or NH3 ) 6 can fit around central metal ion (octahedral shape )
- bigger ligands ( Cl- ) = 4 can fit around central metal ion
Six co-ordinate bonds
- have octahedral shape
- many octahedral complex ions are hexaaqua complexes = there are six water ligands around central ion
Four co-ordinate bonds
- usually have tetrahedral shape
- but few complexes = four co-ordinate bonds form a square planar shape ( Cisplatin )
two co-ordinate bonds
- some silver complexes have 2 co-ordinate bonds and form a linear shape
Optical isomerism
- for complex ions, optical isomers form when an ion can exist as 2 non-superimposable mirror images
- happens in octahedral complexes when 3 bidentate ligands are attached to central ion
- optical isomers = also known as enantiomers
Cis-trans isomerism
- another type of stereoisomerism
- square planar complex ions that have 2 pairs of ligands show cis-trans iso
- either cis or trans
2 ligands directly opposite to each other
trans
2 paired ligands right next to each other
cis
