5.3.2 - Transition Metals. Flashcards
Definitions, Colours, Reactions and Complexes.
What is the DEFINITION of a Transition Metal?
A d-block element which forms at least 1 ion with an incomplete d-orbital/ sub-shell.
Which 2 elements in the first row of the d-block have unusual electron configurations?
- Chromium (4s1 3d5).
- Copper (4s1 3d10).
Which 2 elements in the first row of the d-block are NOT transition elements?
Scandium (Sc) and Zinc (Zn) because they are not able to form at least 1 ion with an incomplete d-orbital/ sub-shell.
Why is the d-block called the “d-block”?
Because the highest energy electrons are in the d orbitals/sub-shell.
Give 3 chemical properties of transition elements and their compounds.
- They can form multiple oxidation states.
- They can form coloured compounds.
- They can act as catalysts.
Give 3 physical properties of transition elements.
- High Melting and Boiling Points.
- They are malleable (can be shaped).
- They are good conductors of heat and electricity.
What is the DEFINITION of a ligand.
A ligand is a species (molecule or ion) that can donate a pair of electrons to a central metal ion to form a coordinate/dative covalent bond.
What is the DEFINITION of a coordination number.
The amount of coordinate bonds which a metal ion forms in a complex ion.
What is the DEFINITION of a dative/ coodinate bond.
A covalent bond which has been formed where one of the bonded atoms has donated both electrons in its shared pair to a central metal ion in a complex ion.
What is the DEFINITION of a ligand substitution reaction.
A reaction where one ligand in a complex ion is substituted by another ligand.
What is the DEFINITION of a complex ion?
A transition metal ion bonded to one or more ligands by coordinate (dative covalent) bonds.
Give some examples of a neutral ligand.
- Ammonia :NH3
- Water H20:
Give some examples of a charged ligand.
- Hydroxide :OH-
- Cyanide :CN-
- Chloride :Cl-
Explain what a MONODENTATE ligand is and give an example.
- A ligand which forms 1 coordinate (dative covalent) bond to a central metal ion in a complex ion.
- NH3, H2O, OH-, CN-, Cl-.
Explain what a BIDENTATE ligand is and give an example.
- A ligand which forms 2 coordinate (dative covalent) bonds to a central metal ion in a complex ion.
- (en) NH2CH2CH2NH2.
Explain what a HEXADENTATE ligand is and give an example.
- A ligand which forms 6 coordinate (dative covalent) bonds to a central metal ion in a complex ion.
- (edta4-).
What is the colour of Cu2+(aq)?
Blue Solution.
What colour is the precipitate formed by adding NaOH dropwise to Cu2+(aq)? What is the ionic equation for the formation of this?
- Blue Precipitate.
- Cu2+(aq) + 2OH-(aq) → Cu(OH)2(s).
What is the colour of Fe2+(aq)?
Pale Green Solution.
What colour is the precipitate formed by adding NaOH dropwise to Fe2+(aq)? What is the ionic equation for the formation of this?
- Dark Green Precipitate which goes brown standing in air.
- Fe2+(aq) + 2OH- → Fe(OH)2(s).
What is the colour of Fe3+(aq)?
Pale Yellow Solution.
What colour is the precipitate formed by adding NaOH dropwise to Fe3+(aq)? What is the ionic equation for the formation of this?
- Orange-brown Precipitate.
- Fe3+(aq) + OH-(aq) → Fe(OH)3(s).
What is the colour of Mn2+(aq)?
Pale Pink Solution.
What colour is the precipitate formed by adding NaOH dropwise to Mn2+(aq)? What is the ionic equation for the formation of this?
- Light brown Precipitate which darkens on standing in air.
- Mn2+(aq) + OH-(aq) → Mn(OH)2(s).
What is the colour of Cr3+(aq)?
Violet Solution.
What colour is the precipitate formed by adding NaOH dropwise to Cr3+(aq)? What is the ionic equation for the formation of this?
- Grey-green precipitate.
- Cr3+(aq) + OH-(aq) → Cr(OH)3(s).
What colour is the precipitate formed by adding NaOH in excess to Cr3+(aq)? What is the complex ion which is formed?
- The precipitate dissolves and a Dark Green Solution is formed.
- [Cr(OH)6]3-(aq).
What colour is the precipitate formed by adding NH3 dropwise to Cu2+(aq)? What is the ionic equation for the formation of this?
- Blue Precipitate.
- Cu2+(aq) + 2OH-(aq) → Cu(OH)2(s).
What colour is the solution formed by adding NH3 in excess to Cu2+(aq)? What is the equation for the formation of this?
- The precipitate dissolves and a Dark Blue Solution is formed (LIGAND EXCHANGE).
- [Cu(H2O)6]2+(aq) + 4NH3(aq) —> [Cu(NH3)4(H2O)2]2+(aq) + 4H2O(l).
What colour is the precipitate formed by adding NH3 dropwise to Cr3+(aq)? What is the ionic equation for the formation of this?
- Grey-green precipitate.
- Cr3+(aq) + 3OH-(aq) → Cr(OH)3(s).
What colour is the solution formed by adding NH3 in excess to Cr3+(aq)? What is the equation for the formation of this?
- The precipitate dissolves and a Purple Solution is formed (LIGAND EXCHANGE).
- [Cr(H2O)6]3+(aq) + 6NH3(aq) —> [Cr(NH3)6]3+(aq) + 6H2O(l).
What colour change do you see when Cl-(aq) ions are added to Cu2+(aq)? What is the equation of the reaction that takes place?
- Blue Solution to Yellow Solution.
- [Cu(H2O)6]2+ + 4Cl- ⇌ [CuCl4]2- + 6H2O.
What two shapes and bond angles could a 4-coordinate complex have?
- Tetrahedral (109.5°).
- Square Planar (90°).
When filling or removing electrons in an atom, is 4s or 3d filled/ removed first?
4s.
What shape and bond angle does a 2-coordinate complex have?
Linear (180°).
What shape and bond angle does a 6-coordinate complex have?
Octahedral (90°).
Identify 1 transition metal used as a heterogeneous catalyst.
Iron (Fe) in the Haber Process or Nickel (Ni) in the hydrogenation of alkenes.
What is cis-platin and how does it work? Give it’s formula.
- Cis-platin is a chemotherapy drug which binds to the DNA of cancer cells preventing cancer cell division.
- [Pt(NH3)2(Cl)2].
What type of isomerism can you get with octahedral complexes with 2 or more bidentate ligands?
Optical Isomerism.
Explain what happens to Haemoglobin in the lungs and close to respiring cells.
- Lungs: Oxygen (O2) binds to Haemoglobin to make Oxyhaemoglobin when oxygens concentration is high.
- Respiring Cells: O2 ligand of Oxyhaemoglobin is substituted by CO2 to make Carboxyhaemoglobin.