Transition Metals
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- Created by: Jessinoch
- Created on: 24-11-17 12:08
Transition Metal
A metal that can form one or more stable ions with a partially filled d sub-level.
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Why aren't scandium, zinc and titanium transition metals?
Sc only forms ions of Sc3+ which has an empty d sub-level. Zn only forms ions of Zn2+, which has a full d sub-shell. Ti forms ions of Ti2+ which has a incomplete d sub-level.
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4 Physical Properties of Transition Metals and Explain
1. High density (atoms close together due to smb) 2. High melting and boiling points (lots energy to break smb) 3. Hard and rigid (useful as construction materials - atoms firmly in place smb) 4. Good conductors of electricity (delocalised electrons)
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What are the chemical properties of transition metals?
1. Complex ions 2. Coloured ions 3. Catalysts 4. Variable Oxidation States
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What are complexes?
A central metal atom or ion surrounded by co-ordinately bonded ligands.
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Ligands that can only form one co-ordinate bond
Monodentate - H2O, NH3, Cl-, CN-, OH-
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Ligands that can form two co-ordinate bonds
Bidentate - C2O42-, en
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Ligands that can form more than two co-ordinate bonds
Multidentate - EDTA4-
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State the origin of transition metal complexes
Electron electrons get excited in d shell and emits energy in visible range
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3 changes to a transition metal complex resulting to a change of colour
1. Different oxidation states 2. Different ligands 3. Different coordination number
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Explain why metal(II) ions do not usually form octahedral complexes when chloride ions are the only ligands?
The chloride ion is too big and repels.
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Why is the titration between MnO4- and C2O42- so slow at first?
The ions repel
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Autocatalytic
A product of the reaction acts as a catalyst
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D-block Element
Element that has its highest energy (outermost) electron in a d sub-level.
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Properties of scandium and zinc
1. Have only one oxidation state 2. Have little catalytic activity 3. Form white compounds
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Why do transition metals exhibit variable oxidation states?
Often have a large number of electrons occupying 4s/3d oribitals, which are similar energy and far away from nucleus. Electrons can be lost from both, less energy required to remove electrons in 4s and 3d sub levels.
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How can the maximum possible oxidation state of a transition metal be predicted?
It is often equal to the total number of 4s and 3d electrons.
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What are the shapes and angles of the complex ions?
CN 2, linear, 180. CN 4 (large ligands), tetrahedral, 109.5. CN 4 (pt complexes), square planar, 90. CN 6, octrahedral, 90.
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What does the shape of the complex ion depend on?
1. the nature of the metal 2. the nature of the ligand 3. the size of the metal ion 4. the charge on the metal ion
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What does the colour of the ion depend on?
1. metal 2. oxidation state 3. ligands 4. coordination number
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What are the two main uses of colorimetry?
1. to find an unknown concentration of a given complex. 2. to identify the ion to ligand ratio in a given complex.
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How can you find the complex ion formulae using colorimetry?
1. light of a certain wavelength passed through solution 2. different solutions prepared where concentrations are altered 3. absorbance of each mixture plotted 4. mixture with greatest absorbance identifies ratio of ligands within complex
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What is homogeneous and heterogeneous?
Homogeneous - the catalyst is in the same physical state as the reactions. Heterogeneous - the catalyst is in a different physical state than the reactants.What i
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What is the surface adsorption theory?
Happens in heterogeneous catalysts. The reactant molecules are adsorbed onto catalyst surface forming weak bonds. Reaction occurs forming products. Product molecules desorbed from catalyst surface and diffuse away.
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What is the contact process?
1. SO2 + V2O5 -> SO3 + V2O4 2. V2O4 + 1/2O2 -> V2O5 (Heterogeneous catalyst)
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Manufacture of methanol
CO2 + 2H2 -> CH3OH (catalysed by chromium (III) oxide (Cr2O3)
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The haber process
N2 + 3H2 -> 2NH3 (catalysed by iron)
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Examples of catalytic poisoning
1. the catalyst in catalytic converters is poisoned by lead 2. the fe catalyst in haber process is poisoned by sulphur impurities from the methane to manufacture hydrogen gas used
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What is catalytic poisoning?
A catalyst can be rendered inactive if impurities block the active sites - increase of impurities can reduce the efficiency of the catalyst and increase costs.
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Coordinate bond
Shared or pair of electrons come from one atom
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Examples of Complex Ions and their uses
Haemoglobin - contains Fe2+ allowing o2 to be carried. [Pt(NH3)2Cl2] - cis platin anti-cancer drug. [Ag(NH3)2]+ tollen's reagent (aldehyde/ketone) [Ag(CN)2]- silver electroplating [Ag(S2O3)2]3- formed in photography to removed unreacted AgX from film
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What are the elements that have exceptions to the electron configuration rule?
Copper and chromium
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Coordination number
The number of atoms or ions (ligands) covalently bonded to a central metal ion by coordinate bonds
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Other cards in this set
Card 2
Front
Why aren't scandium, zinc and titanium transition metals?
Back
Sc only forms ions of Sc3+ which has an empty d sub-level. Zn only forms ions of Zn2+, which has a full d sub-shell. Ti forms ions of Ti2+ which has a incomplete d sub-level.
Card 3
Front
4 Physical Properties of Transition Metals and Explain
Back
Card 4
Front
What are the chemical properties of transition metals?
Back
Card 5
Front
What are complexes?
Back
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