Quiz | The Chemistry of the Transition Metals

1

Which of the following properties is not a characteristic of transition metal ions?

Form colored solutions

Variable oxidation states

Act as strong acids

Act as catalysts

Transition metal ions can have variable oxidation states (ex: Iron ⇒ Fe2+ and Fe3+)

Transition metal complexes are generally used as catalysts

The 5 d-orbitals of a transition metal ion can be divided into 2 sets: the d electrons can then make a transition by absorbing light ⇒ this explains the color of many coordination compounds

2

Which of the following statements about [Pt(NH3)2Cl2] is incorrect?

Its name is diamminedichloroplatinum (II)

Its coordination number is 4

It can exhibit cis and trans isomers

None of the above

3

What is the geometry of [Co(NH3)6]2+?

Linear

Tetrahedral

Square Planar

Octahedral

[Co(NH3)6]2+: 6 NH3 ligands around the central ion Co2+ ⇒ octahedral geometry
The most common geometries are linear (2 ligands), tetrahedral, square planar (4 ligands) and octahedral (6 ligands)

4

What is the electron configuration of Fe2+ (Fe: Z = 26)?

[Ar] 3d6

[Ar] 3d4 4s2

[Ar] 3d5 4s1

[Ar] 3d6 4s2

Iron is an element of the group 8 and has 26 electrons: Fe: [Ar] 3d64s2
In all the chemistry of the transition metals, the 4s orbital behaves as the highest energy orbital compared to 3d orbitals ⇒ Fe2+: [Ar] 3d6

5

What is the electron configuration of the d-orbitals of [FeF6]4- (high spin)?

eg6

t2g6

eg4 t2g2

t2g4 eg2

Oxidation state of Fe in [FeF6]4-: +2 ⇒ Fe2+: [Ar] 3d6 
High-spin configuration: splitting energy Δo < pairing energy ⇒ the d-electrons occupy the eg orbitals before they pair up in the t2g orbitals
Electron configuration of the d-orbitals of [FeF6]4​​​​​​​: t2g4 eg2

6

In which configuration is K4[Fe(CN)6] diamagnetic?

Octahedral configuration

Low-spin configuration

High-spin configuration

All of the above

Oxidation state of iron in K4[Fe(CN)6]: +2 ⇒ Fe2+: [Ar] 3d6

Low-spin configuration: the electrons first fill the t2g orbitals before occupying the higher-energy eg orbitals ⇒ electron configuration is t2g6 and all electrons are paired ⇒ diamagnetic compound

High-spin configuration: the d-electrons occupy the eg orbitals before they pair up in the t2g orbitals ⇒ electron configuration is t2g4 eg2 and 4 electrons are unpaired ⇒ paramagnetic compound