Transition Elements Flashcards
what is a transition element
an element that can form ATLEAST 1 stable ion with a partially filled d orbital
what happens to the electrons in 4s orbital of Cr
the one electron moves to the 3d orbitals so they all have one electron each- more stable
what happens to the electrons in 4s orbital of Cu
one electron goes to the 3d orbital so all the 3d orbitals are full- results in the 4s orbital only having 1 electron
why isn’t Sc a transition element
forms Sc3+ but has an EMPTY sub shell
why isn’t Zn a transition element
forms Zn2+ but has a FULL d sub shell
what colour is [Cu(h2o)6]2+
pale blue
what happens to [Cu(h2o)6]2+ when SOME OH- is added formula of ion + colour
[Cu(h2o)4(OH)2] or [Cu(OH)2] and a pale blue precipitate forms
formula of ion formed when excess NH3 is added to [Cu(H2O)6]2+ and colour
[Cu(NH3)4(H2O)2]2+ Dark blue solution
what colour is [Fe(h2o)6]2+
pale green
what happens to [Fe(h2o)6]2+ when SOME OH- is added formula of ion + colour
[Fe(h2o)4(OH)2] or [Fe(OH)2] a dirty green ppt forms
what colour is [Fe(h2o)6]3+
yellow
what happens to [Fe(h2o)6]3+ when SOME OH- is added formula of ion + colour
[Fe(h2o)3(OH)3] or [Fe(OH)3] a orange/ brown ppt forms
what colour is [Mn(h2o)6]2+
Pale pink
what happens to [Mn(h2o)6]2+ when SOME OH- is added formula of ion + colour
Mn(h2o)4(OH)2] or [Mn(OH)2] a brown ppt forms
what colour is [Cr(h2o)6]3+
green
what happens to [Cr(h2o)6]3+ when SOME OH- is added formula of ion + colour
[Cr(h2o)3(OH)3] or [Cr(OH)3] a green/grey ppt forms
what happens to [Cr(h2o)6]3+ when EXCESS OH- is added formula of ion + colour
[Cr(OH)6]3- a Dark green solution
formula of ion formed when excess NH3 is added to [Cr(h2o)6]3+ and colour
[Cr(NH3)6]3+ a purple solution
what is a complex ion
a central transition metal ion is surrounded by ligands bonded by dative covalent (coordinate) bonds
ligands have…
at least 1 lone pair of electrons to form a coordinate bond with the transition metal
examples of monodentate ligands
H2O, NH3, CN-, Cl-
examples of bidentate ligand (2)
ethandioate and ethane 1,2 diamine
what is ligand shape determined by
ligand size + number of coordinate bonds
structure of cis platin and what its used for
(cl)2pt(NH3)2
both the cl displace easily and bond to N atoms on the DNA of cancer cells- preventing cancer cells from reproducing
disadvantage of cisplatin
prevents normal cells from reproducing - including blood cells- suppresses immune system
when can optical isomerism occur in ligands
when octahedral complexes are formed by 3 bidentate ligands bonded to a central ion
why are transition elements good catalysts
can change oxidation states by gaining/ losing electrons within their d orbitals- this transfer of electrons speeds up reactions.
also good at adsorbing substances onto their surfaces to lower eA
positives of using transition elements as catalysts
good for industry and environment- allow reactions to occur at lower temperatures and pressures.
negatives of using transition elements as catalysts
health risks- some are toxic
long term exposure to copper-liver +kidney damage
Mn causes psychiatric problems
what happens when carbon monoxide bonds to haem
replaces the water ligand- its a very strong ligand doesn’t readily exchange with o2 or h2o
oxidation of Fe2+
by acidified KMnO4 goes from pale green to Fe3+ (yellow)
reduction of Fe3+
by I- goes from yellow to pale green Fe2+
oxidation of Cr3+
oxidised to (Cr2O4)2- by warming with H2O2 in alkaline conditions.
colour of (Cr2O4)2-
yellow
how to make (Cr2O7)2-
add dilute h2so4
colour of (Cr2O7)2-
orange
reducing (Cr2O7)2- to Cr3+ (what is needed)
acidified zinc
reducing cu2+ (what is needed and what is made)
I- is needed and CuI(s) is made
colour of CuI (cu+) ppt
white ppt
2CuI(s) + I2 is made from reducing Cu2+ what is observed in the test tube
CuI forms a white ppt and I2 results in a brown solution
what happens to Cu+
readily disproportionates to produce Cu(s) and Cu2+ (aq)
colour of Cu(s)
brown
Cu(s) + Cu2+(aq) is made from disproportionation of of Cu+ what is observed in the test tube
Cu(s) forms a brown solid and Cu2+ forms a blue solution
