Transition Metals Flashcards
Define transition element.
A d-block element capable of forming at least one stable ion with a partially filled d-subshell.
Give the electron configuration of Chromium from [Ar]
[Ar]3d5 4s1
What is the pattern for successive ionisation energies of transision elements?
Since the d-orbitals are very close in energy, the successive ionisation energy is low, meaning many ions can be formed with minimal energy.
What type of equation do you use to show precipitation of transition metals?
Therfore, what must you do?
Ionic equations, so you must cancel all the spectator ions, and only separate those which are in solution.
Define Ligand
A species with a lone pair of electrons which it donates to a central metal ion to form a dative covalent bond.
Define complex ion.
A transition metal ion bonded datively to at least one ligand.
Define co-ordination number.
The number of dative bonds between the central metal ion and its ligands.
What class of species can we clasify many ligands as and why?
Think organic mechanisms.
They are nucleophiles as they have a lone pair which they can donate to an electron deficient area to form a dative bond.
What are the three shapes most commonly found in TM complexes?
Octahedral - 90, CN=6
Square Planar (Cis-platin) - 90, CN=4
Tetrahedral (CuCl4) - 109, CN=4
Define denticity
The number of donor groups in a single ligand that can bind to the transition metal ion in a co-ordinated complex.
What does a chiral compound do optically?
It rotates the plane of polarised light by 90
Name these ligands:
H2O
OH-
NH3
Cl-
CN-
SCN-
H-
F-
Aqua
hydroxo
amine
chloro
cyano
thiocynano
hydrido
fluoro
Which name do we use for cations or neutral compounds?
Standard metal name, e.g. hexa aqua COPPER
Which name do we use for anions?
Cu - cuperate
Fe - Ferrate
Cr - Chromate
Co - Coboltate
Al - Aluminate
What happens when H2O ligands bond to a transition metal ion?
They change shape from 104.5 to 107, as a lone pair becomes a bonded pair.
In the reaction of copper ions with ammonia, what is the intermediate step. Why does this form?
Cu(OH)2 is the intermediate, because of the amphotericity of NH3
NH3+H2O –> NH4++OH-
What is the colour change whe Cl2(aq) reacts with hexa aqua copper? What is the shape of the product formed?
Blue solution –> yellow solution. Equilibrium means green is the final colour change
Tetrahedral shape since Cl- is a large ligand.
What is the colour change when Co2+ reacts with Cl-(aq)? What is the shape of the complex?
Pink solution –> blue solution
Tetrahedral shape as Cl- is a large ligand.
What makes transition metals good catalysts?
High surface area and many oxidation states leading to a wide range of possible intermediates.
What is the colour change when NaOH reacts with Copper
blue solution to pale blue precipitate
What is the colour change when NaOH reacts with Cobolt?
Pink solution to blue precipitate in colourless solution
What is the colour change when NaOH reacts with Fe2+
pale green solution to green precipitate
What is the colour change when NaOH reacts with Fe3+
Pale yellow to brown precipitate
Which 3 ligand combinations can lead to optical isomerism?
stereoisomers
3 bidentate
2 bidentate +2 monodentate
EDTA
What two requirements must be met to have cis-trans isomerism? (shape and ligands)
square planar/octahedral
2 ligands different to others.
Define ligand substitution
One ligand is replaced by another ligand in a transition metal complex.
What is the ratio of MnO4 to Fe in a redox titration?
1:5
What is the colour change when NH3 reacts with Cu
A blue precipitate forms which becomes a blue solution on excess NH3
The atomic number of iron is 26. What is the electron configuration from [Ar] of Fe2+?
[Ar]4s2 3d6
Fe2+ = [Ar]3d6
The atomic number of manganese is 25. What is the electron configuration from [Ar] of Mn2+?
[Ar]4s2 3d5
2+ = [Ar]3d5
What is the shape of [CuCl4]2-
Tetrahedral.
State 3 properties of Fe2+ that are characteristic of transition metal ion.
forms complex ion, coloured compounds formed, catalyst
How is oxygen transported in the body?
Oxygen bonds to iron transition metal ion, and detached when it reaches its destination.
Why does CO cause less oxygen to be transported?
Complex ion with CO is more stable with CO than with O, and the Fe-CO bond is stronger than Fe-O bond
Draw the structure of 1,1-cyclobutanedicarboxylate
.
What is the colour change when an iodine - thiosulphate titration reaches the end point without starch
Yellow -> colourless
What is the colour change when starch is add to iodine-thiosulphate titration?
black -> colourless
What is the colour change for Fe/MnO4- titration
colourless-pink
What is the colour change in iodine thiosulphate titration with starch?
Black to colourless
What is the benefit of adding starch to iodine thiosulphate titration? What does it react with?
Clearer colour change from black to colourless than yellow to colourless. Starch goes black in presence of I2 and is colourless in presence of I-
What are the three things that are typical reactions of transition metals?
precipitation, ligand substitution, redox
