2.5 Transition Metals

Question 1

What are the properties of a transition metal?

Answer 1

3d Block
Forms one or more stable ions which have partially filled d orbitals
Forms complex ions
Forms colour compounds
Variable oxidation states
Catalytic activity

Question 2

What is a ligand?

Answer 2

A ligand is a molecule or ion that forms a co-ordinate bond with a transition metal by donating a pair of electrons

Question 3

What are examples of mono dentate ligands?

Answer 3

H2O
NH3
Cl-

Question 4

What is the co-ordination number?

Answer 4

The total number of co-ordinat ends formed between the central ion and the ligand

Question 5

What is a bidentate ligand?

Answer 5

Donates 2 lone pairs

H2NCH2CH2NH2

Question 6

What is a multi dentate ligand?

Answer 6

Donates many lone pairs

EDTA -4

Question 7

What are the shapes that ligands can find?

Answer 7

Linear
Square Planar
Tetrahedral
Octahedral

Question 8

What are Cis/Trans Isomers?

Answer 8

A special case of E/Z isomers

Question 9

What is Cisplatin?

Answer 9

An anticancer drug which binds to Guanine in DNA

H3N—-Pt—–NH3
Cl——- ——-Cl

Question 10

What is Transplatin?

Answer 10

An isomer of Cisplatin which has no use in medicine as it is toxic

Question 11

What is Haemoglobin?

Answer 11

Iron surrounded by Haem group
Hollow ring (Porphyrin) of carbon and hydrogen attached to N which donates e- pair
Found in RBC

Question 12

Why is Carbon monoxide poisoning toxic? Transition Metals?

Answer 12

The CO replaces O2 with a more stable bond preventing oxyhemoglobin forming and requires a high O2 saturation to reverse.

Question 13

What is Chelation?

Answer 13

Replacing simple ligands with multi dentate ligands like EDTA
Used for pt. with metal poisoning to remove the metal.
A chelate is more stable than unidentate ligands

Question 14

What is EDTA?

Answer 14

Ethylenediamine tetra acetic acid

Donates 6 lone pairs

Question 15

Why does the Chelate effect work?

Including EDTA example

Answer 15

2 reactions may have the same enthalpy but different entropy (amount of species)

EDTA bonds, allowing more species to be removed from ligand so increases entropy.

To reverse an entropic increase requires a lot of energy so is difficult to revers

[Cu(H2O)6] + EDTA →

[Cu(EDTA)] + 6H2O

We go from 2 species to 7

Question 16

What do coloured compounds depend on?

Answer 16

Transition element
Oxidation state
Ligands
Co-ordination number

Question 17

How do coloured compounds form?

Answer 17

The e- in the partially filled d orbital is excited to a higher energy, absorbing energy
The energy that isn’t absorbed is shown as a colour reflected.

Question 18

Colour Compound Equation

Answer 18

Energy Difference=

wavelength

∆H = (hc)/ λ

Question 19

What is the importance of coloured transition metals?

Answer 19

We can use colorimetry to find the concentration

Question 20

What are heterogenous catalysts?

Answer 20

Different phase to reactants
Increase SA
Spread on support medium Easily poisoned and efficiency reduced

Question 21

What is the Haber Process Catalyst

Answer 21

N2 + 3H2 ⇌ 2NH3
Iron Catalyst (Heterogenous)
Pea sized lumps to incr. SA
Poisoned in 5 years by gases

Question 22

What is the Contact Process Catalyst?

Answer 22

2SO2 + O2  ⇌ 2SO3
V2O5 catalyst (Heterogenous)

SO2+ V2O5 → SO3 + V2O5
2V2O5 + O2 → 2V2O5

Question 23

What is homogenous catalyst?

Answer 23

The same state as the reactants

Question 24

What is the Iodine Process catalyst?

Answer 24

Iron Catalyst (Homogenous)
S2O8-² +2I- → 2SO4-² + I2

The two negative ions would repel so catalyst provides an alternate route

Question 25

What is autocatalysis?

Answer 25

One of the products acts as a catalyst