3.2.5 Transition metals

Question 1

What is a transition metal?

Answer 1

is a d-block element that can form at least one stable ion with a partially filled (incomplete) d-subshell.

Question 2

How many elements are there in the 3-d block?

Answer 2

10 elements which are metals.

Question 3

How many elements in the 3-d block are transition metals?

Answer 3

8
Ti - Cu form coloured compounds.

Question 4

Outline the reason why Scandium and Zinc are not transition metals.

Answer 4

They don’t form a stable ion with a partially filled d-subshell

Question 5

Outline electronic configuration of Sc and then Sc^3+

Answer 5

Sc: [Ar] 4s2 3d1
Sc^3+: [Ar]

no electrons in d subshell.

Scandium only forms a 3+ ion. -> must be able to form one stable ion with a partially filled d-subshell.

TRANSITION METAL is a d-block element that can form at least one stable ion with a partially filled (incomplete) d-subshell.

Question 6

Outline the electronic configuration of Zn and Zn^2+

Answer 6

Zn: [Ar] 4s2 3d10
Zn^2+: [Ar] 3d10

Zn2+ has a full d-subshell.
It is not partially filled.

TRANSITION METAL: is a d-block element that can form at least one stable ion with a partially filled (incomplete) d-subshell.

Question 7

How does chromium behave differently than the other transition metals?

Answer 7

[Ar] 4s2 3d4 - orignal
[Ar] 4s1 3d5
one of the electrons from the 4s orbital moves down to a lower orbital with higher energy
Half full d orbital is more stable than having the other electron paired up in the 4s orbital.
3d4 = ↑,↑,↑,↑ 4s2 = ↑,↑
3d5 = ↑,↑,↑,↑,↑ 4s1= ↑ = more stable.

Question 8

How do copper behave differently than the other transition metals?

Answer 8

[Ar] 4s2 3d9
[Ar] 4s1 3d10
It is more stable for copper to have a fully paired 3d sub shell.
1 electrons drops from the 4s subshell to achieve this and becomes [Ar] 4s1 3d10.

Question 9

What are the properties of transition metals?

Answer 9

1. Complex formation = ligands form coordiante bonds to a metal ion.
2. Formation of coloured ions
3. Variable oxidation states
   4.Catalytic activity.

Question 10

Define a ligand.

Answer 10

A molecule or ion that forms a coordinate bond with a transition metal by donating a pair of electrons / has at least 1 lone pair of electrons.

Question 11

Define mono / unidentate ligands and outline some examples.

Answer 11

Forms only one coordinate bond with the transition metal.

examples:
H2O:
:NH3
:Cl-
:OH-
:CN

i.e: [Cu(H2O)6]2+

Question 12

Define bidentate ligands and outline some examples.

Answer 12

Forms 2 coordinate bonds with the transition metal.

example:
ethanedioate = C2O4^2-
ethane1,2-diamine = H2NCH2CH2NH2

Question 13

Define multidentate ligands and outline some examples.

Answer 13

Forms several coordiante bonds.
example: EDTA^4- and Haem in haemoglobin.

Question 14

Define complex shape.

Answer 14

Central metal atom or ion surrounded by ligands.

Question 15

Define Co-ordination number.

Answer 15

Number of coordination bonds to the central metal atom or ion.

Question 16

How to work out oxidation state of a metal ion.
[CuCl4]^2-

Answer 16

Total oxidation state of metal = Total oxidation state - Total oxidation state of ligands

each Cl- ligand = -1
-1 x 4 = -4

total oxidation state = -2

Oxidation state of Cu = -2 - (-4)
Oxidation state of Cu = +2

Question 17

Coordination number = 2

What is the shape, bond angle, occurenence and an example of this?

Answer 17

Shape: Linear
Bond angle: 180
Occurenece: Ag+ complexes
Example: [Ag(NH3)2]^+

= Tollens’ reagent to distinguish between aldehydes and ketones.

Question 18

Coordination number = 4

What is the shape, bond angle, occurenence and an example of this?

Answer 18

Shape: tetrahedral
Bond angle: 109.5
Occurenece: Large ligands (:Cl^-)
Example: [CuCl4]^2-

Question 19

Coordination number = 4

What is the shape, bond angle, occurenence and an example of this?

Answer 19

Shape: Square planar
Bond angle: 90
Occurenece: Pt^2+ complexes
Example: [PtCl4]^2-

= anti cancer drug cis platin

Question 20

Coordination number = 6

What is the shape, bond angle, occurenence and an example of this?

Answer 20

Shape: Octahedral
Bond angle: 90
Occurenece:
Example: [Cu(H2O)6]^2+

Question 21

What type of ligand is haem in haemoglobin?

Answer 21

Mutlidentate ligand.

Question 22

Outline the role of haemoglobin.

Answer 22

Haemoglobin = protein

Transports oxygen around the body in blood.

4N come from 1 multidentate ligand = haem

One coordinate bond = large protein called globin

Final coordinate bond = oxygen or water

Question 23

How does haemoglobin transport oxygen around the body?

Answer 23

1. Oxygen subsitutes the water ligand in the lungs where oxygen concentration is high forming oxyhaemoglobin = transported around the body.
2. Oxyhaemoglobin gives up O2 to a place where it is needed for example to the muscle cells for respitation.
3. water takes the place of oxygen. Haemoglobin returns back to the lungs and repeats cycle.

Question 24

What is carbon monoxide?

Answer 24

Poisonous gas that causes headaches, unconsciousness or death = silent killer

Question 25

How is carbon monoxide poisonous?

Answer 25

1. If CO is inhaled, H2O ligand is replaced with CO ligand.
2. CO bonds strongly to the Fe = cannot be readily replaced by oxygen or water.
3. Oxygen cannot be transported = oxygen starvation in organs
   example: Brain is starved of O2 = headaches or unconsciousness.