quizlet transition metal deck

• Write the electron configuration of Cr

  1s22s22p63s23p64s13d5
• Write the electron configuration of Cu

  1s22s22p63s23p64s13d10
• Which subshell do period 4, d block elements lose electrons from first?

  4s
• Explain which period 4 d block elements are not transition elements


  Zinc only forms a stable ion with a full d subshell: Zn2+ (3d10)
• State the physical properties of transition metals

  Metallic) High melting and boiling points

  Good conductors (of heat and electricity)

  Hard/ strong Low reactivity (chemical property)
• State some uses of transition metals

  Copper: water pipes Iron: vehicle bodies, reinforce concrete Titanium: jet engine parts
• Define: coordinate bond


  A covalent bond where both electrons come from the same atom
• Define: ligand

  A molecule or ion that forms a co-ordinate bond with a transition metal by donating a pair of electrons (lone pair).
• Define: complex ion

  A central metal ion surrounded by co-ordinately bonded ligands
• Explain how a coordinate bond is formed in a transition metal complex

  An electron pair on the ligand is donated to the central metal ion
• Define coordination number

  The number of co-ordinate bonds to the central metal atom or ion.
• State four chemical characteristics common to the transition metals

  1) Variable oxidation states 2) Form coloured ions 3) Exhibit catalytic activity 4) Complex formation
• Why do transition metals have variable oxidation states?

  They have a partially filled d-subshell so can lose 4s and 3d electrons as they are similar in energy
• Which oxidation states are common to all transition metals except Sc?

  1+ and 2+ due to losing the 4s electrons
• Define: aqua ion

  An ion formed when a metal ion dissolves in water and is surrounded by 6 water molecules (acting as ligands). This forms an octahedral complex.
• Draw the aqua ion formed when Fe(||) dissolves

  
• Define: Lewis acid

  Lone pair acceptor
• Define: Lewis base

  Lone pair donor
• Define: monodentate ligand

  A ligand which forms one co-ordinate bond to a metal ion (one lone pair to donate) e.g. H2O, NH3, Cl-, CN-
• Define: bidentate ligand

  A ligand that has two atomsthat each donate a lone pair to a central metal ion e.g.ethane-1,2-diamine (en): H2NCH2CH2NH2,ethanedioate: C2O42-benzene-1,2-diol: C6H4(OH)2
• Draw ethane-1,2-diamine (en)

  
• Draw ethanedioate

  
• Define: multidentate ligand

  Ligands which form more than two co-ordinate bonds to a central metal ion (e.g. EDTA4- )
• How many coordinate bonds does EDTA form?

  6
• State the shape and bond angle(s) of a complex ion with a coordination number of 6

  Octahedral, 90o
• State the shape and bond angle(s) of a complex ion with a coordination number of 2

  Linear, 180o
• Give an example of a linear complex ion


  [Ag(NH3)2]+
• How do you work out the oxidation state of the metal in a complex ion?

  -Complex charge & sum of ligand charges
• Which complex ion shapes can exhibit cis trans isomerism?

  Octahedral ions □ planar ions
• How can these complex ions display cis

  -2 identical ligands on the same side of the metal ion = cis

  -.2 identical ligands on opposite sides of the metal ion = trans
• What is haemoglobin?

  A red pigment in blood made up of 4 globin chains, each containing a haem molecule
• What is haem?

  A complex ion where Fe2+ has a co-ordination number of 6. It is complexed to the porphyrin ring system (tetradentate ligand), a nitrogen on the globin protein chain, and it can accept an O2 molecule as its final ligand.
• How does haem release oxygen?

  The bond between Fe2+ and O2 is weak so oxygen can easily diffuse into cells.
• Why is carbon monoxide poisonous?

  CO is a better ligand than O2 so it binds to Fe2+ irreversibly and prevents haemoglobin in red blood cells from transporting oxygen around the body.
• Why are transition metal compounds coloured?

  -The d electrons transition from the ground state to an excited state as they absorb energy in the visible range.

  -The remaining wavelengths are transmitted (if aqueous) or reflected (if solid) --The complex appears a combination of the remaining colours
• What could result in a change in colour of a transition metal complex?

  -Change in oxidation state

  -Change of ligands

  -Change in co-ordination number
• What is a colorimeter

  An instrument which measures the absorbance of a particular wavelength of light by a solution. The greater the absorbance, the higher the concentration of the solution.
• The energy difference between the ground state and the excited state of the d electrons is given by:


  ∆E = hν = hc/λ Units: ∆E (J) h (Js) ν (Hz) c (ms-1) λ (m)
• Outline a plan to determine the concentration of transition metal ions in a solution of unknown concentration

  1Add an appropriate ligand to intensify colour

  .2Make up solutions of known concentration 3.Use a colorimeter to measure absorption or transmission of these solutions

  4 Plot a calibration curve (concentration vs absorbance)

  5Measure the absorption of the unknown solution and determine the concentration using the calibration curve
• Suggest why it is important that in colorimetry the container for each sample has the same dimensions

  Absorption depends on (is proportional to) distance travelled through solution