TRANSITION ELEMENTS
1
TRANSITION ELEMENTS
These are large block of elements in the central position of periodic table, bridging the
s-block elements at the left and p-block elements at the right (see figure next slide has
the details)
They are often divided into two groups, depending on the valence electrons
involved in their chemistry
❑ The fist group are the d-block elements because their occurrence in the periodic
table coincides with the filling of d orbitals
❑ The second group is the f-block elements, characterized by filling f-orbitals.
Contained within this there are two subgroups; the lanthanides elements and the
Actinides elements
2
3
This lecture focuses primarily on the d-block elements, and within this
group we concentrate mainly on the elements in the fourth period or the
elements of the first raw transition series , scandium (SC) to zinc (Zn)
4
Transition element is the phrase/term used to describe elements in the d
and f block of the periodic table. They are termed transition because their
positions in the periodic table is between the s and p block elements
❑ In the s and p blocks, elements displays strong similarities and
noticeable trends across the period and down the groups of the
periodic table.
❑ The same trends are observed in the d and f block elements.
❑ The first row transition elements and their electron configuration are
shown in Table 1
5
Table 1: First row transition elements and their electronic configuration
Element
Symbol
Electron
configuration
Sc (Z = 21)
[Ar]3d14s2.

Titanium
Ti (Z = 22)
[Ar]3d24s2.


Vanadium
V (Z = 23)
[Ar]3d34s2.



Chromium
Cr (Z = 24)
[Ar]3d54s1.






Manganese
Mn (Z = 25)
[Ar]3d54s2.






Iron
Fe (Z = 26)
[Ar]3d64s2.






Cobalt
Co (Z = 27)
[Ar]3d74s2.






Nickel
Ni (Z = 28)
[Ar]3d84s2.






Copper
Cu (Z = 29)
[Ar]3d104s1.






Zinc
Zn (Z = 30)
[Ar]3d104s2.






Scandium
3d
4s



6
The term transition element and d-block elements are not sometimes the
same.
For example:
✓Sc (Z = 21) with an electron configuration of [Ar]3d14s2 forms Sc3+ with
electron configuration of [Ar]3d04s0 in its all compounds.
✓Zn (Z = 30) with an electron configuration of [Ar]3d104s2 forms Zn2+ with
electron configuration [Ar]3d10 in its compounds.
✓Copper (Z = 29) with configuration of [Ar]3d104s1 has an electron configuration
of [ Ar]3d9 in its common occurring +2 oxidation State..
According to International Union and Pure Applied Chemistry (IUPAC), a
transition element is defined as an element whose atom has an incomplete
filled d-sub-shell or an element that give cations with incomplete filled dsub-shell.
7
According to IUPAC definition of transition elements,
Scandium (Sc) and Zinc (Zn) are not strictly transition elements
but are d-orbital elements because (why)
they do not show characteristic
features of transition elements like
colored
compounds
and
paramagnetism
They have d0 or d10 configuration.
Others are cadmium (Cd) and
mercury
(Hg).
Copper
with
[Ar]3d104s1 electron configuration is a
transition element because it has
[Ar]3d94s2 electron configuration in its
commonly occurring +2 Oxidation
State.
However, exception electron configuration is for Chromium (Z = 24) as
[Ar]4s13d5 and not [Ar]4s23d4; Copper (Z = 29) as [Ar]4s13d10 and not
[Ar]4s23d9 (why irregularities?)
8
Explanation
This kind of irregularities is due to extra stability associated with halffilled and complete filled 3d-orbitals. For TMs forming cations,
electrons are removed from the 4s orbitals than from 3d orbitals.
In atoms of these transition elements, the 3d and 4s orbitals have similar
energies. The 4s orbitals are conveniently described as the outer-most
orbitals. This is because of the radial probability plots of the 3d and 4s
orbitals (Figure 2) indicates that there is a greater probability of the 4s
electrons being furthermore from the nucleus.
9
4s electrons are far from the
nucleus as compared to those of
3d electrons as shown by their
radial probability function or
plots
Figure 2. The radial probability plots of 4s and 3d 0rbitals
10
Properties of the transition elements
(a)
The d-block metals include elements with a wide range of
properties. They encompass
➢ the most common metal used in construction and manufacturing (iron),
➢ metals valued for their beauty (gold, silver, and platinum),
➢ metals used in coins (nickel, copper, and zinc).
➢ metals used in modern technology (titanium)
➢ metals known and used in early civilizations (copper, silver, gold, and iron).
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Properties of the transition elements
(b)
The d-block contains
• the densest elements : Osmium, d = 22.49 g/cm3, and iridium, d
= 22.41 g/cm3),
✓ the metals with the highest and lowest melting points (tungsten,
MP = 3410 °C, and mercury, MP = −38.9 °C)
✓ two elements with atomic numbers less than 83 that have only radioactive
isotopes [Technetium, Tc, atomic number 43; Promethium, Pm, atomic
number 61, in the f -block].
12
They have a metallic luster and conduct
electricity and heat.
(c) With the exception
of mercury, the
transition elements
are solids
They react with various oxidizing agents to give
ionic
compounds,
although
there
is
considerable variation in such reactions among
the elements.
They are used for jewelry and decorative items
because silver, gold, and platinum resist
oxidation
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(d) Certain d-block elements are important in living organisms.
❑ Cobalt is the crucial element in vitamin B12, which is part of a
catalyst essential for several biochemical reactions.
❑ Hemoglobin and myoglobin, oxygen-carrying and storage
proteins, contain iron.
❑ Molybdenum and iron, together with sulfur, form the reactive
portion of nitrogenase, a biological catalyst used by nitrogenfixing organisms to convert atmospheric nitrogen into ammonia
(NH3)
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(e) Many transition metal compounds are highly colored, so making them good
candidates for pigments in paints and dyes
Prussian blue,
Fe4[Fe(CN)6]3•14H2O,
This is a bluing agent
used in engineering
blueprint and in
boundary to brighten
yellowed white cloth
A common pigment
(artist Cd yellow)
contains CdS
Titanium (IV) oxide
(TiO2) a whitish in
most white paints
15
(f) Presence of TM cations (ions)
• Crystalline silicate
• Crystalline silicate
Transforms them into gemstones
→ Fe2+ ions produces the yellow colour in citrine
→ Cr3+ ions produces red colour of ruby
(g) TM compounds: Small quantities adds colour to glass. For
example
→ Blue glass contains small amount of Co(II) oxide
→ Addition of Cr(III) oxide to glass gives a green colour
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→
Window panes and doors sometimes take on a purple color over
time as a consequence of oxidation of traces of manganese (II) ion
present in the glass to permanganate ion (MnO4−).
Shah Mosque, Iran
Basilica of St Peter and Paul
17
Importance of Transition Metals
The d-block elements or metals have great importance in our daily lives. They are
building blocks for life. For example:
❑ They are chief structural materials
❑ They are good electrical conductors such as silver and copper
❑ Compounds of transition elements like those of Ti, Fe and Cr are primarily
constituents of paint pigments
❑ Are essential materials for photography
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❑ Compounds of f-block elements are used in a number of application
such as
➢ colored TV screen
➢ photocopiers,
➢ efficient green emitting plasma display panels, etc.
Lanthanide orthophosphate (LaPO4) doped with Cerium (Ce) or terbium (Tb) is
deposited layer onto TV glass screen producing intense green Luminescence
19
Are good candidates as semiconductor materials (ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe
InAs etc)
A device emitting in the near-IR spectral region with an external efficiency
of ~0.5% based on InAs/ZnSe core-shell nanocrystals has been reported
20
Transition metal complexes plays an important role in
biological processes like storage. For example
Iron as TM performs many vital functions in the
human body
Fe is an essential trace element for
human
body.
For
example:
Haemoglobin
is
the
O-transport
metalloprotein in the red blood cell
Myoglobin facilitates the O2
and storage in the muscles.
Cytochrome transports
electrons
21
• Fe is an integral part of enzyme in various tissue. For
example an average 70 kg adult body contains around
4200 mg of Fe ions (65%) The majority can be found
as Haemoglobin or myoglobin which are classified as
function of Fe
• Fe is mainly stored in mammals as ferritin, which is
essential as core of hydrated iron (III) oxide coated
with protein.
• The structure of Hemoglobin is as shown in the next
slide
22
The structure of haemoglobin
23
24
▪ Detoxification (a process by which a living organism converts
unwanted species into harmless substance), and
▪ Structural role (metaloproteins) like the influence of zinc metal in
the structure of protein-zinc insulin complexes)
▪ Plays an important roles (TMs) in polymerization process and
therapeutic uses (where complexes and complexion agents are
utilized to treat a variety of diseases (the aspect of medicinal
chemistry-knowledge
of
the
role
of
metals
physiological and pathological states of the body)
in
the
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❑ TM complexes are species consisting of a transition metal
coordinated or bonded to one or more ligands (neutral or anionic
non metal species) and are important in catalysts, material
synthesis, photochemistry and biological systems.
❑ TM complexes also display diverse chemical, optical and magnetic
properties
26
Common Physical Properties of Transition Elements
➢ are metals
➢ their reactivity vary from moderate to active to inert
➢ their outermost s orbital and first d (3d) orbital of TEs comprises their
valence electrons/ shells of TEs
• Some or all of the electrons in s and d orbital are used when TMs forms
compounds
• Exhibit rich and fascinating chemistry with a variable of
oxidation states and forms colored compounds due to the
presence of a partially filled orbital.
TMs and their compounds are useful as pigments in paints
and dyes. e.g: Prussian blue (Fe[Fe(CN)6]3) is a bluing
agent in laundry bleach and in engineering blue imprints
27
❑ TM ions in crystalline silicates or alumina, such as minerals
becomes gems (in Swahili vito) such as Tanzanite, Ruby etc. For
example:
✓ Rubies contains Cr3+ substituted for some of the Al3+ ions in a
crystal lattice of Al2O3. The TM ions gives the red color to the
material and this is the reason why rubies can function as lasers
✓ Blue glasses are made by adding a small amount of Co2+ salts
✓ The green patina on copper statues and roofs is an oxidation
form of copper
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❑ TM are hard, strong, high
melting and boiling point, forms
alloys with one another and with other metallic elements
❑ TM Forms colored compound with exception a few, exhibit
variable oxidation state (oxidation number), d and f block
elements forms array of coordination compounds.
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❑ TM have several oxidation states
❑ TM are often paramagnetic
❑ TM have high heat of fusion and evaporation
❑ Atomic parameters of TMs (most of them) increases across the
period from left to right (For example: atomic numbers, nuclear
charge increases because electrons are added to the outer shells
and the nuclear charge increases due to increase of protons).
❑ TM have incompletely filled d-orbital (sub-shells)
The Physical Properties of First Row Transition Elements (Fourth
Period Elements are summarized in the Table (next slide)
30
Table: Electron Configuration and other Properties of the First Raw Transition Elements
Electron
configuration
M
SC
TI
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
4s23d1
4s23d2
4s23d3
4s13d5
4s23d5
4s23d6
4s23d7
4s23d8
4s13d10
4s23d10
M2+
-
3d2
3d3
3d4
3d5
3d6
3d7
3d8
3d9
3d10
M3+
[Ar]
3d1
3d2
3d3
3d4
3d5
3d6
3d7
3d8
3d9
EN
1.3
1.5
1.6
1.6
1.5
1.8
1.9
1.9
1.9
2
1st IE (kJ/mol)
631
658
650
652
717
759
760
736
745
906
2nd IE (kJ/mol)
1235
1309
1413
1591
1509
1561
1645
1751
1958
1733
3rd IE (kJ/mol)
2389
2650
2828
2986
3250
2956
3281
3393
3578
3833
4th IE (kJ/mol)
7130
4173
4600
4900
5020
5510
5114
5404
5683
M
162
147
134
130
135
126
125
124
128
M2+
-
90
88
85
80
77
75
69
72
M3+
81
77
74
64
66
60
64
-
-
SEP (Volt)
-2.03
-1.63
-1.13
-0.90
-1.18
-0.44
-0.28
-0.26
0.35
-0.763
MP (C)
1539
1668
1900
1875
1245
1536
1495
1453
1083
419
BP (C)
2730
3260
3450
2665
2150
3000
2900
2730
2595
906
3.0
4.51
6.1
7.19
7.43
7.86
8.9
8.9
8.96
7.14
31
Radius(pm)
Density /gcm-3
133
-
 The trend in IE of the TE/TM as shown in the Table above, shows
some features of transition metal chemistry. Generally, the ionization
energies doubles as the oxidation states/number increases by a unit
(Table above). The 4th IE of scandium shows that Sc(IV) is unlikely to
occur, where as Ti(IV) and V(IV) for instance do not occur commonly.
 Many factors are important in determining the stability of OXIDATION STATES.
Thus we cannot decide which OXIDATION STATE will occur on the basis of
IONIZATION ENERGIES alone. The unipositivity of TE are not
normally stable in aqueous solution because of the SIGNIFICANT
SUBLIMATION ENERGY TERM in the process
H SUBLIM
+
H HYDR
+
M(s) ⎯⎯ ⎯
⎯→ M(g) ⎯⎯→ M (aq) ⎯⎯ ⎯
⎯→ M (aq)
IE
32
❑ Metal Atomic Radius
The radii of the transition elements vary over a fairly narrow range, with a
small decrease to a minimum being observed around the middle of this
group of elements
This similarity of radii can be understood
based on electron configurations. Atomic
size is determined by the electrons in the
outermost orbital, which for these
elements is the ns orbital (n = 4, 5, or 6).
Progressing from left to right in the periodic
table, the size decline expected from
increasing the number of protons in the
nucleus is mostly canceled out by an
opposing effect, repulsion from additional
electrons in the (n − 1)d orbitals
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❑ Density
The variation in metal radii causes the densities of the transition elements to first
increase and then decrease across a period (Figure below). Although the overall
change in radii among these elements is small, the effect is magnified because the
volume is actually changing with the cube of the radius [V = (4πr3/3].
34
The lanthanide contraction explains why elements in the sixth period have the
highest densities. The relatively small radii of sixth-period transition metals,
combined with the fact that their atomic masses are considerably larger than their
counterparts in the fifth period, causes sixth-period metal densities to be very large.
Read
One result of the Lanthanide contraction is the greatest density of such as
Platinum and Gold. The relative small radii of 6th period TMs combined with the
fact that their mass is considerably large than their counterpart in the 5th period
cause 6th period metal densities to be very large. For instance Platinum is one of
the most dense metal known.
Lanthanide contraction is the shrinkage of atoms following
the filling of the 4f (i.e. f ) subshell (that is atoms are smaller
than expected)
35
❑ Melting and Boiling Points
The melting and boiling points of any substance reflects the forces of attraction
between the atoms, molecules, or ions that compose the solid.
Melting and boiling points (molar enthalpy of fusion) of transition elements are very
high due to strong metallic bonding in in TE (metal), which occurs due to the
delocalization of electrons facilitated by the availability of both d and 2 electrons.
With TEs, the MP and BP rises to a maximum around the middle of the series and
then descends as shown in the pot of melting and boiling points of transition elements
(see figure next slide).
36
Figure. (a)
Variations of MP of 1st, 2nd and 3rd raw transition elements (b)
Variation of Boiling and Melting points of First Raw (fourth period)
Transition Metals/Elements
The observed dip (depression) at Mn (3d5) and Zn (3d10) are caused by
extra stability of half filled and full filled d-sub-shells. These electron
arrangement makes them less available for contribution to the pool of
metallic bonding hence weakening the metallic bond. This gives rise to the
decrease of melting and boiling points.
37
❑ Reactivity of Transition Metals
Transition metals displays an increasing tendency to remain unreactive or noble.
This is favored by:
✓ high heat of sublimation,
✓ high ionization energy and
✓ low heat of solvation.
The high melting points suggest high heat of sublimation and the smaller the
atom the greater the ionization energy (IE). The tendency is most pronounced in
Platinum and Gold (underactivity)
❑ Ionization Energy
The ease with which an electron may be removed from transition metal atom is
intermediate between those of s and p block elements. This suggest that the
transition elements (metals) are less electropositive than group 1 and 2 and may form
ionic or covalent bond depending on the condition..
38
Generally,
▪ the lower valence states are ionic
▪ higher valence states are covalent.
▪ The tendency of the ionicity decreases as the atom gets larger and the
variation of ionization energies within d-block is small in all cases (lies
between 5 and 10 eV ).
39
▪ From Sc to Zn across the period small change in the first and second
ionization energies are observed.
Reason
This is due to the build up of electrons in the immediate underlying dsub-shells that effectively shields the 4s electrons from the nucleus and
minimizing the increase in effective nuclear charge from element to
element. The variation of First ionization energies for First row transition
elements (4th period of periodic table) are as shown in the figure below.
40
However, the increase in the THIRD and FOURTH ionization energies
(table above) are rapid and the values show the usual discontinuity halfway along the series as shown in the plot of 3rd IONIZATION ENERGIES
against increasing ATOMIC NUMBER (Z) of first raw transition elements
(metals)This can be explained as follows:
41
The reason for the observed discontinuity is as follows:
The five d-electrons are all unpaired in singly occupied orbitals. When the
6th and subsequent electrons enters, the electrons have to share (pair)
the already occupied orbital resulting in inter electron –electrons
repulsions, which would require less energy to remove an electron.
Hence, the third ionization energy curve for the last five elements is
identical in shape to the curve for the first five elements, but displaced
upwards by 580 kJ mol-1 as shown in the above plot).
42
Self
Assessment
Question
Use the values of third ionization energies of first
row transition elements given elsewhere to
construct a graph of ionization against first raw
transition metals. Explain the reason for
discontinuity observed in the trend of ionization
energies between manganese (Mn) and iron (Fe)
43
❑ Colour
Many TE/TM ions and complex ions/anions containing TMs are
distinctive colored . The Sc3+, V5+ and Zn2+ ions are colorless
Aqueous solutions of chromium compounds
with two different oxidation numbers: +3 in
Cr(NO3)3 (VIOLET)) and CrCl3 (GREEN), and
+6 in K2CrO4 (YELLOW) and K2Cr2O7
(ORANGE). The two Cr(III) species have
different colors in solution because there are
different complex ions in solution.
44
The origin of the colors of TM ions and TM compounds is due to the
electronic transition involving d-orbital electrons (within partially
filled d-sub-shells). As a results, this imparts colour to solid transition
metal compounds and their solution. Ionic and covalent compounds of
transition elements are usually colored compared to compounds of s and
p block elements, which are usually white and are generally most strong
reducing agents
Color is associated with incomplete electron shell and the ability to
promote an electron from lower energy level to higher energy level.
This can be done by the absorption of light of certain wavelength . In
transition elements, d-electrons are promoted to a higher energy level
within the d-shell. This reflect a fairly small energy difference, the reason
for the absorption in the visible region.
45
❑ Magnetism (Magnetic Properties)
Most of TRANSITION METALS and their compounds
paramagnetic because they attract magnetic lines of force.
pare
The paramagnetic properties is associated with the presence of one
or more unpaired electrons and incomplete filled d-orbitals of the
metals. Other elements (substance) in which all the electron are
paired do not attract lines of force and are termed diamagnetic.
Recall that Fe, Co and Ni are ferromagnetic because they can be
magnetized. They are unique in revealing special magnetic property
hence displaying ferro-magnetism properties, the ability to be made
into permanent magnets
46
❑ Catalytic Properties
Many of TMs and their compounds are excellent/good catalysts for
inorganic and organic reactions including electrochemical processes.
For instance, the use of vanadium pentoxide (V2O5) as catalyst in the
preparation of sulphuric acid (H2SO4):
How
✓ Burning of sulfur (S) in air
S(s) + O2(g) ⎯→ SO2(g)
✓ Converting SO2(g) to sulfur trioxide (SO3) in the presence of V2O5 as
catalyst
2SO2(g) + O2(g)
V2O5
⎯⎯→ 2SO3(g)
SO3(g) + H2O(l) ⎯⎯→
H2SO4(aq)
47
The use of Platinum (Pt) as catalysts inn hydrogenation reaction
48
CHEMICAL PROPERTIES OF TRANSITION METALS
Transition elements tend to be unreactive, when compared to s-block
elements (i.e. they are less reactive than s-block elements). The
unreactiviness tendency can be attached to:
• High sublimation energy
• High ionization energy
• Low enthalpies of solvation
In some cases, TMs are less reactive than they are supposed to be. This
is due to the development of a thin protective layer on their surfaces.
49
All TMs with the exception of noble metals like Cu, Ag, Pt, Au etc., have
negative electrode reduction potentials meaning that they are able or
capable to react with dilute acids liberating hydrogen gas (H2). For
instance:
Cr(s) ⎯→ Cr3+(aq) + 3e; E = -0.90 V (OXIDATION PROCESS)
2H+(aq) + 2e ⎯→ H2(g); E = 0.00 V (REDUCTION PROCESS)
Overall Reaction
Cr(s) + 6H+(aq ⎯→ 2Cr3+(aq) + 3H2(g); E = -0.90 V
50
It should noted that:
✓ In normal circumstances, the forward reaction does not go unless the
protective layer has been removed or dissolved.
✓ The first row transition elements/metals bearing the headed positions
in their group, (refer also other head/first member of each group) are
reactive metals, which undergo reaction with a very large number of
elements.
✓ The chemistry of transition elements (d-block elements) have a number
features which are common with the exception Sc, Zn and Cu. These
features are:
51
• Oxidation States (Variable Oxidation States)
This is the most striking feature of transition elements. Most of the
transition metals exhibit variable oxidation states (OS) in their
compounds by just loosing one or more electrons.
Oxidation state (OS) is a frequently useful concept with apportions
charges and electrons within the complex molecules and ions. Thus
OS is a FORMAL CHARGE rather than statement of charge
distribution within compounds.
The OS of a metal is the formal charge, which would be placed
upon that metal in a purely ionic description.
For instance the metal in the gaseous phase ions M3+ and Cu+
are assigned OS of +3 and +1, respectively
52
The oxidation states of the First Row Transition Elements (4th
period TMs) are shown below (shaded Oxidation States are the
most common and stable while un-shaded are not stable).
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
*2
+7
*3
*6
*6
*6
*5
*5
*5
*5
+4
+4
+4
+4
+4
+4
*3
*3
*3
*3
*3
*3
*3
*2
*2
*2
*2
*2
*2
*2
*2
+1
+1
53
54
❑ The common oxidation states for each element include +2, +3 or both.
❑ The +3 oxidation states are more stable at the beginning of the series, whereas
towards the end the +2 oxidation states are more stable. The reason for this can be
understood by a close examination of the IONIZATION ENERGY PLOTS
5
5
Figure. .Variation of First, Second and Third ionization energies for the first raw
transition metals
The variation of oxidation states (OS) can be graphically represented as
shown below.
• All elements displays the +1 and +2 oxidation state with the exception of SC and
Zn, which forms bonding with the use of 4s electrons
• From Sc to Mn there is an increase of maximum OS. This shows that for these
metals, the maximum OS corresponds to both 4s electrons and all 3d – electrons
56
being used in bond formation.
❑
From Mn to Zn, the maximum OS decreases. This shows that
both 4s electrons and unpaired d-orbital electrons can be used
to form chemical bonds. For instance Co[Ar]3d74s2 has
unpaired d electrons. So its maximum OS is +5 , 2 from 4s
and 3 from 3d electrons.
The above behavior of TMs is contrary to that of the s block
elements, where the valency is equal to the group number
and p-block elements where the valency equal to the group
number or eighty (8) minus the group number.
57
❑
The OXIDATION STATES occurs in a limited extent in the p-
block, but the valence always changes by two.
For instance TiCl3 and TiCl; SnCl4 and SnCl2 and PCl5 and PCl3.
This is due to different causes including the INERT PAIR EFFECT.
Inert pair effect is the reluctance of s-electrons to be unpaired,
promoted or participate in chemical bonding.
58
Factors Influencing the Stability of the Oxidation States
It is not easy to generalize the trend of stability of oxidation
states of transition elements because a host of factors affecting the
stability of the oxidation state. But the following factors are dominant
➢ Electronic configuration (those in the rare gas configuration are
stable)
➢ The ionization energy
➢ The type of ligands
➢ Conditions of the surrounding/environment
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Higher Oxidation States
These are exhibited when the metals are in combination with fluorine
ions or oxide ions. Fluorine and oxide ions are small, highly
electronegative, and hence most difficulty to oxidized ions. Fluorine is
often said to bring out the maximum covalency of any element.
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Low Oxidation States
• Low oxidation stated are favored by ligands that are capable of
bonding by both s-donor and p -acceptor bonds.
In order to do this, the ligands must posses both lone pair electrons
and vacant orbitals of p-symmetry. These electrons from the ligands
are donated along s-bond.
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STUDY QUESTIONS
1. Which of the following transition metal cations are paramagnetic and
which are diamagnetic?: Cr3+, V2+ Ni2+ and Cu+
2. Identify two transition metal cations with each of the following electron
configurations (use the periodic table provided to answer this question)
[Ar]3d6
[Ar]3d10
[Ar]3d5.
[Ar]3d8
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3 Explain how the following properties varies in first raw transition
elements
(a) Ionic character
(b) Basic properties
(c) Ability to form variable oxidation states
(d) Ability to form complexes
4. Copper with its electronic configuration [Ar]3d104s1, is included in
transition elements while zinc (Zn) is not considered as transition
elements. Explain
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5(a)
(b)
(c)
(d)
What is the maximum number of unpaired d electrons that an atom or ion
posses. Give an example of an atom and an ion that have this number
(i) What is the lanthanide contraction?
(ii) How does lanthanide contraction affect atomic size down a group of
transition element
(iii) How does lanthanide contraction influence the density of the elements of
period 6 (i.e. 3rd raw transition elements)
Explain the following
(i) why are paramagnetic ions common among the transition elements but not
in the main group elements
(ii) Why are colored solutions are common among the transition elements, but
not the main group elements
Using the idea of oxidation state or oxidation number, explain the following:
(i) which oxide CrO3 or CrO forms a more acidic aqueous solution
(ii) Which oxide Mn2O3 or Mn2O7 displays more basic behavior
(iii) Which compound does Cr exhibit greater metallic character behavior, CrF2
or CrF6.
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