Transition Metals

Question 1

What block are transition metals?

Answer 1

d-block

Question 2

Why do certain characteristics occur within transition metals?

Answer 2

Due to an incomplete d-sub level in their atoms or ions

Question 3

What characteristic properties are associated with transition metals?

Answer 3

• complex formation
• formation of coloured ions
• variable oxidation states
• catalytic activity

Question 4

What is a ligand?

Answer 4

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

Question 5

Describe the complex that transition metals form?

Answer 5

A central metal atom or ion surrounded by ligands

Question 6

What is the co-ordination number?

Answer 6

The number of co-ordinate bonds to a central atom or ion.

Question 7

What is a lewis base?

Answer 7

Lone pair donor

Question 8

What is a lewis acid?

Answer 8

Lone pair acceptor

Question 9

Give examples of 3 monodentate ligands

Answer 9

H₂O, NH₃ and Cl-

Question 10

Which monodentate ligands are uncharged?

Answer 10

H₂O and NH₃

Question 11

Which transition metal undergoes incomplete substitution reactions?

Answer 11

Copper forms [Cu(NH₃)₄(H₂O)₂]²⁺

Question 12

Why does Cl- form 4 co-ordinate bonds instead of 6?

Answer 12

Because it is larger than the other uncharged ligands

Question 13

Give three factors that cause ΔE to change

Answer 13

• Co-ordination number
• Ligand
• Oxidation state

Question 14

Give two examples of bidentate ligands

Answer 14

• ethane-1,2-diamine

- ethanedioate

Question 15

What are bidentate ligands?

Answer 15

Form two co-ordinate bonds and donate two electron pairs

Question 16

Give two examples of multidentate ligands?

Answer 16

• EDTA⁴⁻

- Haemoglobin

Question 17

What are the uses of EDTA⁴⁻?

Answer 17

• an antidote for metal poisoning, removes it from blood

- anticoagulant, removes Ca²⁺ and prevents blood from clotting

Question 18

What is chelation?

Answer 18

Entropically driven reaction because there are moles on the right side of the arrow. The enthalpy change is close to 0 because you are breaking and forming the same number of bonds.

Question 19

Which transition metal ion is found in haem?

Answer 19

Fe²⁺

Question 20

What co-ordinate bonds are formed in haemoglobin?

Answer 20

• 4 to a porphyrin rig
• 5th to globin protein
• 6th to oxygen (or carbon monoxide)

Question 21

What is the common shape that transition metal complexes form?

Answer 21

Octahedral

Question 22

What types of isomerism that transition metal complexes form and when does this happen?

Answer 22

• Cis-trans: monodentate ligands

- Optical: bidentate ligands

Question 23

What shape do transition metal complexes form with Cl-?

Answer 23

Tetrahedral

Question 24

What type of shape shows cis-trans isomerism?

Answer 24

Square planar

Question 25

What silver complex is used in Tollens reagent?

Answer 25

[Ag(NH₃)₂]⁺

Question 26

Why are transition metals coloured?

Answer 26

Colour arises when some wavelengths of light of visible light are absorbed and the remaining wavelengths are reflected. d electrons are excited from ground level when light is absorbed

Question 27

What is the equation for the energy change when d electrons are excited?

Answer 27

∆E = hν = hc/λ

Question 28

Outline an experiment to determine the concentration of a solution with a colorimeter.

Answer 28

- Add a ligand to intesify the colour - Make up solutions of known concentrations - Measure absorption - Plot results on a graph and draw a curve of best fit - Measure unknown absorption and compare on calibration curve

Question 29

What are the colours of vanadium species in different oxidation states?

Answer 29

``` V²⁺= purple V³⁺= green VO²⁺= blue VO₂⁺= yellow ```

Question 30

What can be used to reduce species of vanadium?

Answer 30

Zinc with sulphuric acid. Hydrochloric acid can't be used because it could be oxidised to toxic chlorine gas

Question 31

Redox titration equation of Fe²⁺ and MnO₄⁻

Answer 31

5Fe²⁺ + MnO₄⁻ + 8H⁺ --> Mn²⁺ + 4H₂O + 5Fe³⁺

Question 32

Redrox titration equation of MnO₄⁻ and C₂O₄²⁻

Answer 32

2MnO₄⁻ +16H⁺ + 5C₂O₄²⁻ --> 2Mn²⁺ + 8H₂O + 10CO₂

Question 33

Explain why iron(III) ions are more acidic than iron(II) ions

Answer 33

- [Fe(H₂O)₆]³⁺ → [Fe(H₂O)₅(OH)]²⁺ + H⁺ - Fe³⁺ ion has higher charge density than Fe²⁺ - weakens O–H bond