Question 1

a. Explain how the crystal field theory can use the magnitude of the splitting energy F1F1F1S1F1F1F10to provide an explanation of the color and magnetic properties of octahedral complexes. b. In promoting an electron from the t₂_g set of orbitals to the e_g set, an octahedral complex absorbs a photon with a wavelength F1F1F1S1F1F1F10 of 523 nm. Calculate the value of F1F1F1S1F1F1F10 in the complex, in kJ/mol.

Accepted Answer

a. The energy needed for a photon to excite an electron from the lower to the higher set of the split d orbitals, will increase as F1F1F1S1F1F1F10 increases. This will mean the complex absorbs at shorter wavelengths, influencing its color. Also, a large splitting energy F1F1F1S1F1F1F10 will tend to produce low-spin complexes.
b. 229 kJ/mol

Question 2

a. How many unpaired 3d electrons will there be in (i) high and (ii) low-spin complexes of Co(II)?
b. How can high and low-spin complexes be recognized and distinguished experimentally?

Accepted Answer

a. (i) high-spin, 3 unpaired electrons
(ii) low-spin, 1 unpaired electron
b. Unpaired electrons interact strongly with a magnetic field, and this property is used to determine the number of such electrons in a complex.

Question 3

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y.  Which one, if any, of the following is a pair of optical isomers?

Accepted Answer

A)   1 and 2
B)   1 and 3
C)   1 and 4
D)   3 and 4
E)   none of the above A

Question 4

Which of the oxidation states of chromium has the largest valence-state electronegativity?

Accepted Answer

A)   chromium(0) 
B)   chromium(II) 
C)   chromium(III) 
D)   chromium(IV) 
E)   chromium(VI)

Question 5

The ground state electronic configuration of Zn2+ is

Accepted Answer

A)   [Ar]4s23d8.
B)   [Ar]4s23d10.
C)   [Ar]4s13d9.
D)   [Ar]3d10.
E)   [Ar]3d8.

Question 6

How many unpaired electrons will there be in a high-spin octahedral complex of Fe(II)?

Accepted Answer

A)   0
B)   2
C)   4
D)   6
E)   none of the above

Question 7

Which one of the following normally acts as a bidentate ligand in complexes with transition metal ions?

Accepted Answer

A)   CN-
B)   EDTA4-
C)   SCN-
D)   ethylene diamine
E)   ethylene, C2H4

Question 8

Which of the following species could exist as isomers?

Accepted Answer

A)   [Co(H2O) 4Cl2]+
B)   [Pt(NH3) Br3]-
C)   [Pt(en) Cl2]
D)   [Pt(NH3) 3Cl]+
E)   none of the above

Question 9

What is the highest possible oxidation state for palladium, Pd?

Accepted Answer

A)   +1
B)   +2
C)   +3
D)   +4
E)   +6

Question 10

When the ethylenediaminetetraacetate ion (EDTA4-) forms a complex with a transition metal ion, how many electrons does it normally donate to the metal?

Accepted Answer

A)   4
B)   6
C)   8
D)   10
E)   12

Question 11

Chromium and manganese are among the transition elements that form several different oxides. Which of the following statements characterize these oxides?

Accepted Answer

A)   As the oxidation number on the metal increases, the valence-state electronegativity increases and the oxides change from acidic to basic.
B)   As the oxidation number on the metal increases, the valence-state electronegativity increases and the oxides change from basic to acidic.
C)   As the oxidation number on the metal increases, the valence-state electronegativity decreases and the oxides change from acidic to basic.
D)   As the oxidation number on the metal increases, the valence-state electronegativity decreases and the oxides change from basic to acidic.
E)   None of the above statements is correct.

Question 12

Give the systematic name for [CoCl3(H2O)]-.

Accepted Answer

A)   cobalt(II)  chloride monohydrate
B)   aquatrichlorocobalt(II) 
C)   aquatrichlorocobaltate(II) 
D)   aquatrichlorocobaltite(I) 
E)   none of the above

Question 13

Which of the following ligands could participate in linkage isomerism?

Accepted Answer

A)   NH3
B)   H2O
C)   NH4+
D)   NO2-
E)   ethylenediamine

Question 14

A certain transition metal complex has the formula MX42+. If the metal ion has a d8 electron configuration, what is the shape of the complex?

Accepted Answer

A)   octahedral
B)   square pyramid
C)   tetrahedral
D)   trigonal pyramid
E)   square planar

Question 15

In the presence of a strong octahedral ligand field, the number of unpaired electrons in Co(III) will be

Accepted Answer

A)   0.
B)   2.
C)   4.
D)   6.
E)   none of the above.

Question 16

A feature of transition metal chemistry is that these elements exhibit multiple oxidation states. Which one of the following elements exhibits the smallest number of different oxidation states?

Accepted Answer

A)   Ti
B)   Cr
C)   Mn
D)   Co
E)   Zn

Question 17

The crystal field splitting energy, F1F1F1S1F1F1F10,

Accepted Answer

A)   is larger for tetrahedral complexes than for octahedral complexes.
B)   depends on the metal but not on the ligand.
C)   determines the color of a complex.
D)   is larger for ionic ligands like chloride than for molecular ligands like carbon monoxide, CO.
E)   determines the charge of a complex.

Question 18

What is the coordination number of cobalt in the complex ion [Co(en)Cl4]-? (en = ethylenediamine)

Accepted Answer

A)   1
B)   2
C)   4
D)   6
E)   8

Question 19

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y.  Which one of the following statements about these structures is incorrect?

Accepted Answer

A)   Structures 1 and 2 are optical isomers.
B)   Structures 1 and 3 are optical isomers.
C)   Structures 1 and 3 are different complexes.
D)   Structures 1 and 4 are geometrical isomers.
E)   Structures 3 and 4 are the same complex.

Question 20

Which of the following ions is least likely to form colored compounds?

Accepted Answer

A)   Mn2+
B)   Cr5+
C)   Sc3+
D)   Fe3+
E)   Co2+

Exam 23: The Transition Elements and Their Coordination Compounds

a. How many unpaired 3d electrons will there be in (i) high and (ii) low-spin complexes of Co(II)? b. How can high and low-spin complexes be recognized and distinguished experimentally?

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y. Which one, if any, of the following is a pair of optical isomers?

Which of the oxidation states of chromium has the largest valence-state electronegativity?

The ground state electronic configuration of Zn²⁺ is

How many unpaired electrons will there be in a high-spin octahedral complex of Fe(II) ?

Which one of the following normally acts as a bidentate ligand in complexes with transition metal ions?

Which of the following species could exist as isomers?

What is the highest possible oxidation state for palladium, Pd?

When the ethylenediaminetetraacetate ion (EDTA^4-) forms a complex with a transition metal ion, how many electrons does it normally donate to the metal?

Chromium and manganese are among the transition elements that form several different oxides. Which of the following statements characterize these oxides?

Give the systematic name for [CoCl₃(H₂O) ]^-.

Which of the following ligands could participate in linkage isomerism?

A certain transition metal complex has the formula MX₄²⁺. If the metal ion has a d⁸ electron configuration, what is the shape of the complex?

In the presence of a strong octahedral ligand field, the number of unpaired electrons in Co(III) will be

A feature of transition metal chemistry is that these elements exhibit multiple oxidation states. Which one of the following elements exhibits the smallest number of different oxidation states?

The crystal field splitting energy, ,

What is the coordination number of cobalt in the complex ion [Co(en) Cl₄]^-? (en = ethylenediamine)

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y. Which one of the following statements about these structures is incorrect?

Which of the following ions is least likely to form colored compounds?

Exam 23: The Transition Elements and Their Coordination Compounds

a. How many unpaired 3d electrons will there be in (i) high and (ii) low-spin complexes of Co(II)? b. How can high and low-spin complexes be recognized and distinguished experimentally?

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y. Which one, if any, of the following is a pair of optical isomers?

Which of the oxidation states of chromium has the largest valence-state electronegativity?

The ground state electronic configuration of Zn2+ is

How many unpaired electrons will there be in a high-spin octahedral complex of Fe(II) ?

Which one of the following normally acts as a bidentate ligand in complexes with transition metal ions?

Which of the following species could exist as isomers?

What is the highest possible oxidation state for palladium, Pd?

When the ethylenediaminetetraacetate ion (EDTA4-) forms a complex with a transition metal ion, how many electrons does it normally donate to the metal?

Chromium and manganese are among the transition elements that form several different oxides. Which of the following statements characterize these oxides?

Give the systematic name for [CoCl3(H2O) ]-.

Which of the following ligands could participate in linkage isomerism?

A certain transition metal complex has the formula MX42+. If the metal ion has a d8 electron configuration, what is the shape of the complex?

In the presence of a strong octahedral ligand field, the number of unpaired electrons in Co(III) will be

A feature of transition metal chemistry is that these elements exhibit multiple oxidation states. Which one of the following elements exhibits the smallest number of different oxidation states?

The crystal field splitting energy, ,

What is the coordination number of cobalt in the complex ion [Co(en) Cl4]-? (en = ethylenediamine)

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y. Which one of the following statements about these structures is incorrect?

Which of the following ions is least likely to form colored compounds?

The ground state electronic configuration of Zn²⁺ is

When the ethylenediaminetetraacetate ion (EDTA^4-) forms a complex with a transition metal ion, how many electrons does it normally donate to the metal?

Give the systematic name for [CoCl₃(H₂O) ]^-.

A certain transition metal complex has the formula MX₄²⁺. If the metal ion has a d⁸ electron configuration, what is the shape of the complex?

What is the coordination number of cobalt in the complex ion [Co(en) Cl₄]^-? (en = ethylenediamine)