3.2.5 Transition metals Flashcards
What is a transition metal?
is a d-block element that can form at least one stable ion with a partially filled (incomplete) d-subshell.
How many elements are there in the 3-d block?
10 elements which are metals.
How many elements in the 3-d block are transition metals?
8
Ti - Cu form coloured compounds.
Outline the reason why Scandium and Zinc are not transition metals.
They don’t form a stable ion with a partially filled d-subshell
Outline electronic configuration of Sc and then Sc^3+
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.
Outline the electronic configuration of Zn and Zn^2+
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.
How does chromium behave differently than the other transition metals?
[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.
How do copper behave differently than the other transition metals?
[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.
What are the properties of transition metals?
- Complex formation = ligands form coordiante bonds to a metal ion.
- Formation of coloured ions
- Variable oxidation states
4.Catalytic activity.
Define a ligand.
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.
Define mono / unidentate ligands and outline some examples.
Forms only one coordinate bond with the transition metal.
examples:
H2O:
:NH3
:Cl-
:OH-
:CN
i.e: [Cu(H2O)6]2+
Define bidentate ligands and outline some examples.
Forms 2 coordinate bonds with the transition metal.
example:
ethanedioate = C2O4^2-
ethane1,2-diamine = H2NCH2CH2NH2
Define multidentate ligands and outline some examples.
Forms several coordiante bonds.
example: EDTA^4- and Haem in haemoglobin.
Define complex shape.
Central metal atom or ion surrounded by ligands.
Define Co-ordination number.
Number of coordination bonds to the central metal atom or ion.
How to work out oxidation state of a metal ion.
[CuCl4]^2-
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
Coordination number = 2
What is the shape, bond angle, occurenence and an example of this?
Shape: Linear
Bond angle: 180
Occurenece: Ag+ complexes
Example: [Ag(NH3)2]^+
= Tollens’ reagent to distinguish between aldehydes and ketones.
Coordination number = 4
What is the shape, bond angle, occurenence and an example of this?
Shape: tetrahedral
Bond angle: 109.5
Occurenece: Large ligands (:Cl^-)
Example: [CuCl4]^2-
Coordination number = 4
What is the shape, bond angle, occurenence and an example of this?
Shape: Square planar
Bond angle: 90
Occurenece: Pt^2+ complexes
Example: [PtCl4]^2-
= anti cancer drug cis platin
Coordination number = 6
What is the shape, bond angle, occurenence and an example of this?
Shape: Octahedral
Bond angle: 90
Occurenece:
Example: [Cu(H2O)6]^2+
What type of ligand is haem in haemoglobin?
Mutlidentate ligand.
Outline the role of haemoglobin.
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
How does haemoglobin transport oxygen around the body?
- Oxygen subsitutes the water ligand in the lungs where oxygen concentration is high forming oxyhaemoglobin = transported around the body.
- Oxyhaemoglobin gives up O2 to a place where it is needed for example to the muscle cells for respitation.
- water takes the place of oxygen. Haemoglobin returns back to the lungs and repeats cycle.
What is carbon monoxide?
Poisonous gas that causes headaches, unconsciousness or death = silent killer
How is carbon monoxide poisonous?
- If CO is inhaled, H2O ligand is replaced with CO ligand.
- CO bonds strongly to the Fe = cannot be readily replaced by oxygen or water.
- Oxygen cannot be transported = oxygen starvation in organs
example: Brain is starved of O2 = headaches or unconsciousness.
