Transition Metals

Question 1

Define transition element.

Answer 1

A d-block element capable of forming at least one stable ion with a partially filled d-subshell.

Question 2

Give the electron configuration of Chromium from [Ar]

Answer 2

[Ar]3d5 4s1

Question 3

What is the pattern for successive ionisation energies of transision elements?

Answer 3

Since the d-orbitals are very close in energy, the successive ionisation energy is low, meaning many ions can be formed with minimal energy.

Question 4

What type of equation do you use to show precipitation of transition metals?

Therfore, what must you do?

Answer 4

Ionic equations, so you must cancel all the spectator ions, and only separate those which are in solution.

Question 5

Define Ligand

Answer 5

A species with a lone pair of electrons which it donates to a central metal ion to form a dative covalent bond.

Question 6

Define complex ion.

Answer 6

A transition metal ion bonded datively to at least one ligand.

Question 7

Define co-ordination number.

Answer 7

The number of dative bonds between the central metal ion and its ligands.

Question 8

What class of species can we clasify many ligands as and why?

Think organic mechanisms.

Answer 8

They are nucleophiles as they have a lone pair which they can donate to an electron deficient area to form a dative bond.

Question 9

What are the three shapes most commonly found in TM complexes?

Answer 9

Octahedral - 90, CN=6

Square Planar (Cis-platin) - 90, CN=4

Tetrahedral (CuCl4) - 109, CN=4

Question 10

Define denticity

Answer 10

The number of donor groups in a single ligand that can bind to the transition metal ion in a co-ordinated complex.

Question 11

What does a chiral compound do optically?

Answer 11

It rotates the plane of polarised light by 90

Question 12

Name these ligands:

H2O

OH-

NH3

Cl-

CN-

SCN-

H-

F-

Answer 12

Aqua

hydroxo

amine

chloro

cyano

thiocynano

hydrido

fluoro

Question 13

Which name do we use for cations or neutral compounds?

Answer 13

Standard metal name, e.g. hexa aqua COPPER

Question 14

Which name do we use for anions?

Answer 14

Cu - cuperate

Fe - Ferrate

Cr - Chromate

Co - Coboltate

Al - Aluminate

Question 15

What happens when H2O ligands bond to a transition metal ion?

Answer 15

They change shape from 104.5 to 107, as a lone pair becomes a bonded pair.

Question 16

In the reaction of copper ions with ammonia, what is the intermediate step. Why does this form?

Answer 16

Cu(OH)2 is the intermediate, because of the amphotericity of NH3

NH3+H2O –> NH4++OH-

Question 17

What is the colour change whe Cl2(aq) reacts with hexa aqua copper? What is the shape of the product formed?

Answer 17

Blue solution –> yellow solution. Equilibrium means green is the final colour change

Tetrahedral shape since Cl- is a large ligand.

Question 18

What is the colour change when Co2+ reacts with Cl-(aq)? What is the shape of the complex?

Answer 18

Pink solution –> blue solution

Tetrahedral shape as Cl- is a large ligand.

Question 19

What makes transition metals good catalysts?

Answer 19

High surface area and many oxidation states leading to a wide range of possible intermediates.

Question 20

What is the colour change when NaOH reacts with Copper

Answer 20

blue solution to pale blue precipitate

Question 21

What is the colour change when NaOH reacts with Cobolt?

Answer 21

Pink solution to blue precipitate in colourless solution

Question 22

What is the colour change when NaOH reacts with Fe2+

Answer 22

pale green solution to green precipitate

Question 23

What is the colour change when NaOH reacts with Fe3+

Answer 23

Pale yellow to brown precipitate

Question 24

Which 3 ligand combinations can lead to optical isomerism?

stereoisomers

Answer 24

3 bidentate

2 bidentate +2 monodentate

EDTA

Question 25

What two requirements must be met to have cis-trans isomerism? (shape and ligands)

Answer 25

square planar/octahedral 2 ligands different to others.

Question 26

Define ligand substitution

Answer 26

One ligand is replaced by another ligand in a transition metal complex.

Question 27

What is the ratio of MnO4 to Fe in a redox titration?

Answer 27

1:5

Question 28

What is the colour change when NH3 reacts with Cu

Answer 28

A blue precipitate forms which becomes a blue solution on excess NH3

Question 29

The atomic number of iron is 26. What is the electron configuration from [Ar] of Fe2+?

Answer 29

[Ar]4s2 3d6 | Fe2+ = [Ar]3d6

Question 30

The atomic number of manganese is 25. What is the electron configuration from [Ar] of Mn2+?

Answer 30

[Ar]4s2 3d5 | 2+ = [Ar]3d5

Question 31

What is the shape of [CuCl4]2-

Answer 31

Tetrahedral.

Question 32

State 3 properties of Fe2+ that are characteristic of transition metal ion.

Answer 32

forms complex ion, coloured compounds formed, catalyst

Question 33

How is oxygen transported in the body?

Answer 33

Oxygen bonds to iron transition metal ion, and detached when it reaches its destination.

Question 34

Why does CO cause less oxygen to be transported?

Answer 34

Complex ion with CO is more stable with CO than with O, and the Fe-CO bond is stronger than Fe-O bond

Question 35

Draw the structure of 1,1-cyclobutanedicarboxylate

Answer 35

.

Question 36

What is the colour change when an iodine - thiosulphate titration reaches the end point without starch

Answer 36

Yellow -> colourless

Question 37

What is the colour change when starch is add to iodine-thiosulphate titration?

Answer 37

black -> colourless

Question 38

What is the colour change for Fe/MnO4- titration

Answer 38

colourless-pink

Question 39

What is the colour change in iodine thiosulphate titration with starch?

Answer 39

Black to colourless

Question 40

What is the benefit of adding starch to iodine thiosulphate titration? What does it react with?

Answer 40

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-

Question 41

What are the three things that are typical reactions of transition metals?

Answer 41

precipitation, ligand substitution, redox