Download Solutions to Chemistry Review Problems

Chapter 23 Review Problems Solutions
1. What is the electron configuration for the transition metal ion in each of the
following compounds?
a. [Ni(H2O)6]Br2
b. (NH4)2[Fe(H2O)2Cl4]
a. Ni2+: [Ar]d8 (lost the 4s electrons)
b. Fe2+: [Ar]d6 (lost the 4s electrons)
2. What is the lanthanide contraction? How does the lanthanide contraction affect
the properties of the 4d and 5d transition metals?
Lanthanide contraction is a term used in chemistry to describe different but
closely related concepts associated with smaller than expected ionic radii of
the elements in the lanthanide series (atomic number 58, Cerium to 71,
Lutetium). The effect results from poor shielding of nuclear charge by 4f
electrons.
In single-electron atoms, the average separation of an electron from the
nucleus is determined by the subshell it belongs to, and decreases with
increasing charge on the nucleus; this in turn leads to a decrease in atomic
radius. In multi-electron atoms, the decrease in radius brought about by an
increase in nuclear charge is partially offset by increasing electrostatic repulsion
among electrons. In particular, a "shielding effect" operates: i.e., as electrons are
added in outer shells, electrons already present shield the outer electrons from
nuclear charge, making them experience a lower effective charge on the
nucleus. The shielding effect exerted by the inner electrons decreases in the
order s > p > d > f. Usually, as a particular subshell is filled in a period, atomic
radius decreases. This effect is particularly pronounced in the case of
lanthanides, as the 4f subshell which is filled across these elements is not very
effective at shielding the outer shell (n=5 and n=6) electrons. Thus the shielding
effect is less able to counter the decrease in radius caused by increasing
nuclear charge. This leads to "lanthanide contraction". The ionic radius drops
from 102 pm for cerium(III) to 86.1 pm for lutetium(III).
Source: Wikipedia
3. Draw all geometric and linkage isomers of Co(NH3)4(NO2)2
A = NO2, B = NH3
For linkage isomers, show one the NO2 ligands connected through the N and through the O.
4. Draw d orbital splitting diagrams for the octahedral complex ions of each of the
following:
a. Fe 2+ (high and low spin)
Strong Field/Low Spin
Weak Field/High Spin
b. Fe3+ ( high spin)
Weak Field/High Spin
5. Draw the following complex ions and then rank them in order of increasing
wavelength of light absorbed.
[Co(H20)6]3+
[Co(CN)6]3- [Co(I)6]3[Co(en)3]3+
All are octahedral complexes. The first three contain 6 monodentate ligands and the
last complex contains three bidentate ligands.
The spectrochemical series helps us to rank the wavelength absorbed.
[Co(I)6]3- > [Co(H20)6]3+ > [Co(en)3]3+ > [Co(CN)6]3
6. Amino acids can act as ligands toward transition metal ions. The simplest amino acid
is glycine (NH2CH2CO2H).
a. Draw a structure of the glycinate anion (NH2CH2CO2-) acting as a bidentate
ligand.
The structure below is just an example of how glycinate can coordinate to
titanium. You could have drawn something very different.
b. Draw the geometric isomers of the square planar complex Cu(NH2CH2CO2)2
Below is an example of a square complex with a generic (AB) bidentate ligand.