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General Chemistry:
An Integrated Approach
Hill, Petrucci, 4th Edition
Chapter 22
The d-Block Elements and
Coordination Chemistry
Mark P. Heitz
State University of New York at Brockport
© 2005, Prentice Hall, Inc.
On the Periodic Table …
d-block elements contain the transition metals
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Relative Orbital Energies in the
Fourth-Period Transition Series
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Fourth-Period Properties
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Atomic Radii
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Oxidation Numbers
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Scandium
Scandium is rather widely distributed in Earth’s
crust, but there is only one mineral from which it
is extracted, thortveitite, Sc2Si2O7
Despite its relative rarity, the
physical and chemical properties
of scandium have been well
characterized. Its chemistry is
based mostly on the Sc3+ ion
Scandium properties resemble main group
metals, particularly aluminum
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Titanium
Titanium is the ninth most abundant element in
Earth’s crust and the second most abundant
transition metal (after iron)
Three desirable properties make titanium a highly
useful metal: (1) low density; (2) high structural
strength, even at high temperatures; and (3)
corrosion resistance
The most important compound of titanium is the
oxide, TiO2, and its most important use is as a
white pigment in paints, papers, and plastics
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Vanadium
Vanadium is reasonably abundant in Earth’s solid
crust, ranking nineteenth among the elements
It is mostly obtained as a by-product of the production
of uranium from carnotite, K2(UO2)2(VO4)2·3 H2O
Vanadium is of interest because of (1) its use as an
alloying element in steel; (2) the catalytic activity
of some of its compounds, principally V2O5; and
(3) the range of oxidation number in its ions
The different oxidation states of vanadium gives a
variety of distinctive colors
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Chromium
The most important source of chromium is the
mineral chromite, FeCr2O4, or FeO·Cr2O3
In addition to its use in alloys,
chromium can be plated onto other
metals, generally by electrolysis from a
solution containing CrO3 in H2SO4
Dichromate ion, Cr2O72–, is a
common oxidizing agent; chromate
ion, CrO42–, is a good precipitating
agent
The name chromium is from chromus (color)
because its compounds exhibit many colors
Chapter 22: d-Block Elements
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Manganese
Manganese is obtained mainly from the mineral
pyrolusite, MnO2
Ferromanganese alloys are wear resistant and shock
resistant and are used for railroad tracks, bulldozers,
and road scrapers
Manganese dioxide is the starting point for making
most other manganese compounds
Potassium permanganate, KMnO4, is an
important oxidizing agent that is used in both
analytical and organic chemistry laboratories
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The Iron Triad: Fe, Co, and Ni
Iron is the fourth most
abundant element in Earth’s
crust. Cobalt and nickel are not
nearly as common, but they are
still sufficiently abundant that
their annual production is
thousands of tons
All three iron triad
elements form 2+ ions
Ferromagnetism is a much stronger magnetic
effect than paramagnetism
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Ferromagnetism and
Paramagnetism
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Heme and Hemoglobin
Transition
metals are
required for
life …
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Important Metals of Group IB
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Zinc
Zinc has many uses, such as in alloys, and is a
good electrical conductor
Brass is a copper alloy having from 20 to 45% zinc
and small quantities of tin, lead, and iron
Zinc oxidizes in air to form a thin, adherent oxide
coating that protects the underlying metal from
further corrosion
Because zinc is more easily oxidized than iron, zinc
is used in making galvanized iron
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Cadmium
Cadmium can substitute for zinc in coating metals
for certain applications
Its primary uses are in alloys and as electrodes in
batteries
Because of its capacity to absorb neutrons,
cadmium is used in control rods in nuclear
reactors
Zinc in trace amounts is an essential element for
humans; cadmium is quite toxic
Its effect may be to substitute for zinc in certain
enzymes
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Mercury
Mercury differs from zinc and cadmium in at least
six significant ways
Mercury forms few water-soluble compounds and
most of its compounds are not hydrated
The physical properties of mercury, especially its
metallic and liquid properties and its high density,
determine many of its uses
Long-term exposure can present a serious health
hazard
Mercury poisons the body’s systems, in part by
interfering with sulfur-containing enzymes
Chapter 22: d-Block Elements
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The Lanthanide Elements
The elements cerium through lutetium comprise
the first series of the f-block and are called the
inner transition elements
These elements are frequently called “rare earths,” a
name of historical origin but a clear misnomer
because several are not rare at all
For many uses, the lanthanides do not have to be
separated from one another. A mixture of the
lanthanide metals with about 25% La is used in
certain steel and magnesium-based alloys. Some of
the oxides are used to color glass
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Terminology for Complexes
A complex consists of a central atom, which is
usually a metal atom or ion, and attached groups
called ligands
The coordination
number is the
total number of
points at which a
central atom or ion
attaches ligands
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Terminology for Complexes
The region surrounding the central atom or ion
and containing the ligands is called the
coordination sphere
A substance
consisting of one
or more complexes
is called a
coordination
compound
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Cobalt(III) Coordination Cmpds
If a complex carries a net electric charge, it is
called a complex ion
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Ligands
Many metal atoms and ions have empty orbitals
that can accommodate electron pairs
Ligands with one donor atom have just one point of
attachment to the central metal atom or ion and are
called monodentate ligands
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Ligands
Polydentate refers to multiple points of attachment
by one ligand
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Naming Complex Ions
In naming a complex, first name the ligands and
then the central metal atom or ion as a single
compound word
Name the ligands in alphabetical order based on
the first letters of their names and ignoring prefixes
Designate the number of ligands with prefixes
Use the unmodified name of the central metal in
a complex cation. In a complex anion, add the
ending -ate to the name of the central metal
Write the names in the order of cation followed
by anion
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Some Metals in Complex Anions
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Isomerism in Complex Ions
Structural isomers differ in the ligands that are
attached to the central atom or in the donor atoms
through which the ligands are bonded
Geometric isomers differ in the arrangement of the
attached ligands, forming either cis- (same side) or
trans- (opposite sides) compounds
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Optical Activity
Optical isomers are isomers that differ in their
ability to rotate the plane of polarized light
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Optical Activity
Each of the two molecules or ions of an optical
isomer is called an enantiomer and each
enantiomer rotates the plane-polarized light in
opposite directions
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Crystal Field Theory
The attractions between a central atom or ion and
its ligands are largely electrostatic
To predict the magnetic
properties of a complex ion,
its structure and the ability of
its ligands to split the dorbital energy levels must be
known
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d-Level Splitting
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Crystal Field Theory
The spectrochemical series shows the relative
abilities of some common ligands to split the dorbital energy levels
Ligands that produce large energy separations
between groups of d orbitals are called “strong field”
ligands, and those that produce small separations are
“weak field” ligands
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Color in Complex Ions
Many complex ions
are colored because
the energy differences
between d orbitals
match the energies of
components of visible
light
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Effect of Ligands on Colors
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Non-visible Transitions
Ions having the following electron configurations
have no electron transitions in the energy range of
visible light
noble-gas electron configuration
An outer shell with 18 electrons
An “18 + 2” configuration (for
example, Sn2+)
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Chelates
Chelates generally are much more stable than
complexes with monodentate ligands
The increase in entropy during chelation is an
important factor in the stabilities of chelates
EDTA (ethylenediaminetetraacetic acid) is
commonly used to sequester metal ions in
solution
Chelation therapy is sometimes used to treat
heavy metal ion poisoning
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A Metal–EDTA Complex
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Summary of Concepts
• All the elements of the d block are metals
• Most metals exist in several oxidation states and
form many complex ions and colored compounds
• The early members in a period in the d block are
active metals but later members are less active
• Scandium resembles aluminum but is not widely
used
• The uses of titanium depend on its high strength,
low density, and corrosion resistance
• Dichromate and permanganate ions are widely
used oxidizing agents
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Summary (cont’d)
• Copper, silver, and gold are much less active than
earlier members of their periods
• Zinc, cadmium, and mercury are not transition
elements; their atoms and ions all have filled d
subshells
• The central metal atom or ion of a metal complex
is a Lewis acid; it forms coordinate covalent bonds
by accepting lone-pair electrons from ligands,
which are Lewis bases
• Isomerism among complexes is of two general
types: structural and optical
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Summary (cont’d)
• Interactions between lone-pair electrons on
ligands and electrons in the d orbitals of the
central metal atom or ion produce a splitting of the
d-orbital energy level
• Electron transitions between d orbitals of different
energy provide a way for a complex to absorb
some wavelength components of visible light and
transmit others, giving rise to color
• Explanations of the colors and magnetic properties
of complexes are facilitated by a special listing of
common ligands called the spectrochemical series
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