Transition Metals Flashcards
Definition of transition metal
A metal that can form one or more stable ions with a partially filled d sub-level.
Elements in the d block that are not transition metals and why
- Zinc - only forms one ion Zn 2+ which has a full d sub-level
- Scandium - Only form one ion Sc 3+, which has an empty d sub-level
What properties do all transition metals have?
- They all have a high density
- They all have high melting and boiling point
- Their ionic radii are the same
Special chemical properties of transition metals
- They can form complex ions
- They form coloured ions
- They are good catalysts
- They can exist in variable oxidation states
What is a complex ion?
A complex is a central metal atom or ion surrounded by coordinately bonded ligands.
What is a coordinate bond?
A covalent bond in which both electrons in the share pair come from the same atom.
What is a ligand?
A ligand is an atom, ion or molecule that donates a pair of electrons to a central transition metal ion to form a coordinate bond.
What is the coordination number of Cl-?
4 - (too big to form 6)
Equation for oxidation sate of the metal
total oxidation state - the sum of the oxidation states of the ligands
Types of ligands and examples
- monodentate (H2O, NH3, Cl-)
- Bidentate (ethanediamine, ethanedioate)
- multidentate (EDTA)
Equation for energy gap
ΔE = hv = hc/λ
v= frequency of light absorbed (Hz)
h = Planck’s constant (6.63x10-34 J s)
c = speed of light (3.00 x 10^8 m s-1)
λ = wavelength of light absorbed (m)
What effects the size of the energy gap?
- oxidation state
- central metal ion
- ligands
- coordination number
What happens when visible light hits a transition metal ion?
- Some light frequencies are absorbed when electrons jump up to the higher orbitals. The frequencies absorbed depend on the size of the energy gap.
- The rest of the frequencies are transmitted or reflected. The reflected frequencies combine to make the complement of the colour of the absorbed frequencies.
How does spectroscopy work?
- White light is shone through a filter, which is chosen to only let though the colour of light that is absorbed by the sample.
- The light passes through the sample to a colorimeter, which calculates how much light was absorbed by the sample.
- The more concentrated a coloured solution is, the more light it will absorb. This is then used to find out the concentration of the solution of transition metal ions.
Vanadium colours oxidation states and formula
VO2+ (2ox) +5 Yellow
VO +2 (1ox) +4 Blue
V3+ +3 Green
V2+ +2 Violet
Redox Titrations equations
Ethane dioate and manganate
C2O4 —-> CO2
MnO4 —> Mn2+
Fe2+ <—> Fe3+
Generally, what can be used to reduce a transition metal
Zn and H2SO4
Colour of MnO4
Purple
Which two ligands can result in optical isomerism
Ethylenediamine
C2O4-
General equation of metal complex reacting with Chloride ions
[M(H2O)6]2+ + 4Cl —–> [M(Cl)4]2- + 6H2O
Reagents used to reduce vanadium
Zn and H2SO4
Colour and structure of [Co(H2O)6]2+
Octahedral Pink
Colour and structure of [Co(NH3)6]2+
Octahedral straw coloured
Colour and structure of [CoCl4]2-
Tetrahedral blue
Colour ansd structure of [CuCl4]2-
Tetrahedral yellow
Colour and structure of [Fe(H2O)6]3+
Octahedral purple
Colour and structure of [FeCl4]-
Tetrahedral yellow
Haem in haemoglobin
Iron (II) complex with a multidentate ligand (4 nitrogens) (Porphyrin)
Where do other 2 bonds come from in haemoglobin
Protein globin and oxygen/water molecule
Explain how haemoglobin picks up water molecule
In areas of high O2 concerntration- O2 substitutes in for water- oxyhaemoglobin
In areas of low O2 concerntration- H2O subs in for O2
Explain why complex metal ions are acidic in solution
They have a high charge to size ratio
This weakens the OH bonds on the water molecules
More H+ ions are released into solution
Decreasing the PH
What is a chealating ligand
A ligand that forms more than one coordinate covalent bond with central metal ion
Why does a ligand sub reaction aways happen when EDTA is present
EDTA binds more tightly to central ion- Has a chealating effect
Complex formed is more stable
Draw isomers of…
Anti-Cancer drug
Anti-Cancer drug
Explain why different ligands on same central metal ion results in different colour of solution
D orbitals will have different energies
Light energy will be absorbed
Different wavelengths of light will be absorbed
Role of iron in haemoglobin
Oxygen forms a coordinate bond with iron in haemoglobin
Why does carbon monoxide cause death? (describe in terms of transition metals)
Carbon monoxide binds more strongly to iron than oxygen
More stable complex is formed
Prevents oxygen from being transported
Structure of ethanedioate
