Transition Metals

Question 1

What is a complex

Answer 1

A species in which a number of molecules or anions are bonded to a central metal ion by dative covalent bond

Has no overall charge

Question 2

What is a complex ion

Answer 2

Ion in which a number of molecules or anions are bound to a central metal atom by dative covalent bonds

Has an overall charge

Question 3

What is a ligand

Answer 3

Molecule or anion that donates a lone pair of electrons to form a dative covalent bond with a central metal cation

Question 4

What is Co- ordination number

Answer 4

The number of dative covalent bonds formed in a complex

Question 5

What shape and bond angle is formed with a 6 co-ordination number

Answer 5

Octahedral

90degrees

Question 6

What shape and bond angle is formed with a 4 co-ordination number

Answer 6

Tetrahedral
109.5 degrees

OR

Square planar
90 degrees

Question 7

Which 4 co-ordinate number shape is most common and when is the other formed

Answer 7

Tetrahedral is more common

Square planar formed with two seperate monomers

Question 8

What shape and bond angle is formed with a 2 co-ordination number

Answer 8

Linear
180 degrees

Question 9

What is a monodenate ligand

Answer 9

Form one co-ordinate bond per ligand

Question 10

What is a bidenate ligand

Answer 10

Forms two co-ordinate bonds per ligand

Question 11

What is a multidenate ligand

Answer 11

Forms more than two co-ordinate bonds per ligand

Question 12

When is E/Z isomerism used

Answer 12

When there are more than two different groups attached around a C=C double bond

Question 13

What is cis/trans isomerism

Answer 13

When there are only two different groups around a C=C double bond

Question 14

Formula shape and bond angle of cis-platin

Answer 14

[Pt(Cl)2(NH3)]
Square planar
90 degrees

Question 15

Use of cis-platin

Answer 15

Can be used to stop replication of cancerous cells by binding to them

Question 16

Why is trans platin not used

Answer 16

Toxic and ineffective drug

Question 17

Why does the d-orbital split in transition metal complexes

Answer 17

When ligand approach the metal ion, electrons in the ligand repel the electrons in the d-orbital of the metal ion

Causes d sub-shell to split

Question 18

Why is there colour in transition metal complexes

Answer 18

The electrons absorb UV and are excited into space in orbitals above
The change in energy due to this corresponds to UV/ visible light

Colour we see is a mixture of what is not absorbed

Question 19

How is colour seen predicted

Answer 19

Using the colour wheel

Colour seen is opposite to colour absorbed

Question 20

Why is no colour seen in Sc and why is it not a transition metal

Answer 20

No electrons to be promoted
Therefore no colour seen
Thus not a transition metal

Question 21

Why is no colour seen in Zn and why is it not a transition metal

Answer 21

No space in d-orbitals for electron promotion
Therefore no colour
Thus not transition metal

Question 22

Which subshell loses electrons first transition metal

Answer 22

4s electrons lost before 3d electrons

Question 23

Definition of a transition metal

Answer 23

A transition metal is an element that has one or more stable ions with partially filled d orbitals

Question 24

Colour of Cr 3+ ion

Answer 24

Violet

Question 25

Colour of Fe 2+ ion

Answer 25

Green

Question 26

Colour of Fe 3+ ion

Answer 26

Yellow

Question 27

Colour of Cu2+ ion

Answer 27

Blue

Question 28

Colour of Co2+ ion

Answer 28

Pink

Question 29

Colour of Cr3+ and drops of NaOH/HCl

Answer 29

Green

Question 30

Colour of Fe2+ and drops of NaOH/HCl

Answer 30

Green precipitate Oxidises to brown in air

Question 31

Colour of Fe3+ and drops of NaOH/HCl

Answer 31

Brown precipitate

Question 32

Colour of Cu2+ and drops of NaOH/HCl

Answer 32

Blue precipitate

Question 33

Colour of CO2+ and drops of NaOH/HCl

Answer 33

Blue precipitate

Question 34

Colour of Cr3+ and excess NaOH

Answer 34

Green solution

Question 35

Colour of Cr3+ and excess NH3

Answer 35

Purple solution

Question 36

Colour of Cu2+ and excess NH3

Answer 36

Deep blue solution

Question 37

Colour of Co2+ and excess NH3

Answer 37

Brown solution Oxidises in air to form yellow solution

Question 38

Colour of Cu2+ and conc HCl

Answer 38

Yellow

Question 39

Colour of Co2+ and conc HCl

Answer 39

Blue solution

Question 40

What factors affect the colour in a complex ion

Answer 40

The identity of the metal Oxidation state of the metal Identity of the ligands Co- ordination number

Question 41

What is Ligand exchange

Answer 41

When one or more ligands are replaced by other ligands

Question 42

What can ligand exchange cause

Answer 42

A change in co-ordination number A change in colour

Question 43

When is ligand exchange actually acid base

Answer 43

When adding a few drops of OH- or NH3, the OH- or NH3 removes H+ ions from some of the water molecules

Question 44

Reaction of hexaaquacopper and a few drops of dilute ammonia

Answer 44

[Cu(H2O)6]2+ + 2NH3 becomes [Cu(H2O)4(OH)2] + 2NH4+

Question 45

Reaction of tetraaquabihydroxycopper and excess ammonia

Answer 45

[Cu(H2O)4(OH)2] +4NH3 becomes [Cu(NH3)4(H2O)2]2+ + 2H2O + 2OH-

Question 46

Reaction of hexaaquacopper (II) and concentrated HCl

Answer 46

[Co(H2O)6]2+ + 4HCl becomes [Co(Cl)4] + 6H2O + 4H2

Question 47

Why does hexaaquacopper (II) change into tetrachlorocuprate (II)

Answer 47

Because of the size of the Cl- ion, only four can fit around a central metal ion