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Homework 4: Coordination Complexes

There are select solutions to these problems here.


Write the ground-state electron configurations of these transition metal ions: \(V^{5+}\), \(Au^{3+}\), \(Fe^{2+}\), \(Co^{2+}\), \(Ti^{4+}\)?

Q4.1Edit section

Which of these general structures for a complex ion would you expect to exhibit fac and mer isomerism? Explain.

  1. tetrahedral
  2. square-planar
  3. octahedral


If \(\ce{A}\), \(\ce{B}\), \(\ce{C}\), \(\ce{D}\) are four different ligands. How many geometric isomers will be found for square-planar \(\ce{[FeABCD]^2+}\)?


Draw a structure for trans-dichlorobis(ethylenediamine)cobalt(III)ion. What kind of an isomer (geometric or optical) is the cis-dichlorobis(ethylenediamine)cobalt(III)ion.


Not for exam 1


Not for exam 1


Not for exam 1


Not for exam 1


Not for exam 1


Through orbital diagrams, write out the electron configurations for the following transition element atoms or ions:

  1. Fe2+
  2. Co2+
  3. V4+
  4. Sc2+
  5. Ti2+
  6. Cu


Describe the oxidation states, magnetic properties, and trend of atomic radii of the transition metals in period 4.


Balance a potential overall reaction to represent the following equation that uses \(MnO_4\) as an oxidizing agent for the following half reaction:

\[Fe^{2+} (aq) \rightarrow Fe^{3+}(aq) + e^-\]

Assume the reaction is in acidic solution.


Use data and the image provided below to construct standard electrode potentials relating the following manganese species to one another.


What formula would you expect for the metal carbonyls of:

  1. Zirconium (Zr),
  2. Tungsten/wolfram (W),
  3. Platinum (Pt)?
  4. Explain the possible variations that determine the states and structures of different metal carbonyl structures.
  5. For K[Mo(CO)6], how will the structure most likely bond?


 Write the electron configuration for each of the following transition elements and ions.

  1. \(V\)
  2. \(Mn^{3+}\)
  3. \(Fe^{2+}\)
  4. \(Cr\)
  5. \(Co^{2+}\)


Explain how transition elements compare with Alkali metals and Alkali-Earth metals regarding oxidation states, formation of complexes, colors of compounds, and magnetic properties.


Complete and balance the following reaction:

\[Mo_2O_3 (s) + Al (s) \rightarrow\]


Create potential half-reaction equations for the following reactions in acidic solutions.

  1. \(Cr^{3+} (aq)\) as a reducing agent.
  2. \(Sc^{2+} (aq)\) as an oxidizing agent.


Use the given standard reduction potentials to construct a standard electrode potential diagram relation to the following species in acidic solution.


VO2+ (aq) + 2H+(aq) + e- --> V3+ (aq) + H2O (l)    E0= 0.337V

V3+ (aq) + e- ---> V2+ (aq)       E0= -0.255V

V2+(aq) + 2e- --> V(s)      E0= -1.13


What formulas would you expect for the metal carbonyls of:

  1. Tungsten (W)
  2. Ruthenium (Ru)
  3. Technetium (Tc)


Write the electron configurations for the following transition elements: a) Sc b) Cr3+ c) Mn7+ d) Fe2+ e) Cu f) Cu2+

Electronic Configurations


Compare the transition metals with the main group metals.  You may wish to consider oxidation states, formation of complexes, colors of compounds, and magnetic properties.

Oxidation States of Transition Metals


Why does copper react with HCl, but not zinc? 

The reason this happens is because Zn is more reactive than H. This allows the zinc to form a compound with the Cl atoms.

The equation would look like this: Zn (s) + HCl (aq) --> ZnCl2 + H2

Cu is LESS reactive than H so it makes the reaction not possible. 

The Cell Potential


 Write plausible half-equations in acidic solution: 

  1. MnO4- as a reducing agent 
  2. Ni2+ as an oxidizing agent

We can do this by referring to the standard electrode (reduction) potentials. 

a) MnO4- (aq) + 4H+ (aq) + 2e- --> MnO2(s) + H2O (l) 

b) Oxidizing agent = reduced, so you want to flip the equation so the electrons are on the right hand side of the arrows

Ni (s) --> Ni2+ (aq) + 2e

The Cell Potential


Construct a cell diagram from the given reaction couple: Cr3+ / Cr2+ E'cell = -0.9 V ; H+/H2 E'cell = 0 V

Pt (s) l Cr3+(aq) , Cr2+ (aq) ll H+ (aq) l H2 (g) l Pt (s) 

Anode (oxidation) ll cathode (reduction) 

The Cell Potential