S Block

Question 1

What is a transition metal?

Answer 1

An element that possesses a partially filled d sub-shell in its atom or stable ions.

Question 2

Which electrons are lost first when removing electrons from transition metals?

Answer 2

The 4s electrons are lost first.

Question 3

What is the electronic configuration of Scandium (Sc)?

Answer 3

[Ar] 3d¹ 4s²

Question 4

Why is Scandium considered a transition metal?

Answer 4

Because its atom has an incomplete d sub-shell.

Question 5

What is the electronic configuration of Copper (Cu)?

Answer 5

[Ar] 3d¹⁰ 4s¹

Question 6

Why is Copper considered a transition metal?

Answer 6

Because its 2+ ion has an incomplete d sub-shell.

Question 7

What is the electronic configuration of Zinc (Zn)?

Answer 7

[Ar] 3d¹⁰ 4s²

Question 8

Is Zinc a transition metal? Why or why not?

Answer 8

No, because neither its atom nor its ion has an incomplete d sub-shell.

Question 9

What allows transition metals to form different oxidation states?

Answer 9

The similar energies of the 4s and 3d orbitals.

Question 10

List some important oxidation states for Chromium (Cr).

Answer 10

• +3 in Cr2O3
• +6 in Na2Cr2O7 (orange), Na2CrO4 (yellow)

Question 11

List some important oxidation states for Manganese (Mn).

Answer 11

• +2 in MnSO4
• +4 in MnO2
• +7 in KMnO4 (purple)

Question 12

List some important oxidation states for Iron (Fe).

Answer 12

• +2 in FeCl2
• +3 in FeCl3

Question 13

List some important oxidation states for Copper (Cu).

Answer 13

• +1 in CuI (white)
• +2 in CuSO4

Question 14

What role do transition metals play in catalysis?

Answer 14

They are good catalysts.

Question 15

Give examples of transition metals used as catalysts.

Answer 15

• Fe in the Haber process
• Ni in the hydrogenation of alkenes
• V2O5 in the contact process
• MnO2 in the decomposition of H2O2

Question 16

What are the two types of catalysts?

Answer 16

• Homogeneous
• Heterogeneous

Question 17

What is a homogeneous catalyst?

Answer 17

A catalyst in the same physical state as the reactions it catalyzes.

Question 18

What is a heterogeneous catalyst?

Answer 18

A catalyst in a different physical state from the reactions it catalyzes.

Question 19

What is a complex ion?

Answer 19

A metal ion surrounded by co-ordinately bonded ligands.

Question 20

What is a ligand?

Answer 20

A small molecule or ion with a lone pair of electrons.

Question 21

What is the geometry of a tetrahedral complex?

Answer 21

4 ligands arranged around the metal.

Question 22

What is the geometry of an octahedral complex?

Answer 22

6 ligands arranged around the metal.

Question 23

What does the complex ion [CoCl4]⁻ look like?

Answer 23

Blue

Question 24

What does the complex ion [CuCl4]²⁻ look like?

Answer 24

Yellow/green

Question 25

Provide an example of a complex ion and its color.

Answer 25

[Fe(H2O)6]²⁺ - pale green

Question 26

Fill in the blank: A complex ion is a _______.

Answer 26

metal ion surrounded by co-ordinately bonded ligands.

Question 27

What is the color of the complex ion [Cu(NH3)4(H2O)2]²⁺?

Answer 27

Royal blue

Question 28

Reactions with hydroxide ions

Question 29

Ligand exchange

Question 30

When a transition metal ion is exposed to a mixture of ligands

Answer 30

the ligands can be exchanged to

Question 31

form a new complex. This is an equilibrium process

Answer 31

e.g.

Question 32

[Cu(H2O)6]2* + 4NHз = [Cu(NHз)4(H2O)2]* + 4H20

Question 33

If more ammonia is added

Answer 33

the equilibrium shifts to the right

Question 34

and giving a royal blue colour.

Question 35

If more water is added

Answer 35

the equilibrium shifts to the left

Question 36

pale blue colour.

Question 37

Ligand exchange can lead to a change in geometry of the complex ion.

Question 38

[Co(H2O)6]2* + 4Cl- = [CoCl4]2- + 6H2O

Question 39

If a large amount of chloride is used

Answer 39

such as by adding concentrated hydrochloric acid

Question 40

equilibrium shifts from the pink octahedral complex to the blue tetrahedral complex.

Question 41

Transition metal ion

Question 42

[Cr(H2O)6]3+

Question 43

[Fe(H2O)6]2+

Question 44

[Fe(H2O)6]3+

Question 45

[Cu(H2O)6]2+

Question 46

Addition of some OH-

Question 47

Addition of excess OH

Question 48

grey-green ppt of [Cr(H2O)з(OH)3] ppt dissolves giving a deep

Question 49

green solution of [Cr(OH)6]3-

Question 50

dark green ppt of [Fe(H2O)4(OH)2] no further reaction

Question 51

red-brown ppt of [Fe(H2O)3(OH)3] no further reaction

Question 52

pale blue ppt of [Cu(H2O)4(OH)2] no further reaction

Question 53

4. Form coloured complexes

Question 54

Transition metal complexes are almost always coloured. However

Answer 54

in the absence of any ligands around the metal ion

Question 55

Without ligands

Answer 55

a transition metal atom has five degenerate d orbitals

Question 56

different to the other two. This splits the d orbitals to give two sets of orbitals close together in energy.

Question 57

5 degenerate d-orbitals

Question 58

2 d-orbitals

Question 59

3 d-orbitals

Question 60

ATOM

Question 61

OCTAHEDRAL COMPLEX

Question 62

Electrons in the lower 3d orbitals absorb energy from visible light

Answer 62

which promotes them to the higher 3d orbitals. Only one frequency (colour) of light is absorbed

Question 63

between the orbitals. The rest of the frequencies are transmitted; hence

Answer 63

the complementary colour is observed. Compounds containing the complex [Cu(H2O)6]2* are typically blue as they absorb all

Question 64

colours apart from blue.

Question 65

Light absorbed of energy hf

Question 66

OCTAHEDRAL COMPLEX

Question 67

OCTAHEDRAL COMPLEX

Question 68

The energy difference

Answer 68

AE

Question 69

Copper(I) complexes have an electronic configuration with a full d sub-shell which means that there are no empty orbitals to allow electrons to move between energy levels

Answer 69

so copper(I) complexes

Question 70

appear colourless.