1
Q
What is a transition metal?
A
A transition metal is a metal that has an incomplete d subshell either in its neutral atom or in its ions.
2
Q
Why are Zn Cd and Hg not considered transition metals?
A
Because they have completely filled d10 configuration in both ground state and common oxidation states.
3
Q
Why does chromium have the configuration 3d5 4s1 instead of 3d4 4s2?
A
Because the energy gap between 3d and 4s orbitals is small and half-filled d subshell gives extra stability.
4
Q
Why does copper have configuration 3d10 4s1?
A
Due to stability of fully-filled d10 subshell and small energy difference between 3d and 4s orbitals.
5
Q
Why do d orbitals in transition metals influence chemical properties strongly?
A
Because d orbitals extend toward the periphery of the atom and interact strongly with surroundings.
6
Q
What characteristic properties arise from partly filled d orbitals?
A
Variable oxidation states coloured ions and complex formation.
7
Q
Why is scandium considered a transition metal?
A
Because scandium has incompletely filled 3d1 configuration in its ground state.
8
Q
Why is zinc not considered a transition metal?
A
Because zinc has completely filled 3d10 configuration in ground and oxidised states.
9
Q
Silver has d10 configuration in ground state — why is it still considered transition element?
A
Because in excited state it has incomplete config but in ground state full config
10
Q
What typical metallic properties are shown by transition metals?
A
High tensile strength ductility malleability thermal and electrical conductivity and metallic lustre.
11
Q
Which transition metals do not show typical metallic structure at room temperature?
A
Zn Cd Hg and Mn.
12
Q
How hard are transition metals and how volatile are they?
A
They are very hard and have low volatility with high melting and boiling points. With the exception of Zn Cd Hg
13
Q
Why do transition metals have high melting points?
A
Due to involvement of (n−1)d electrons along with ns electrons in strong metallic bonding.
14
Q
Where are melting point maxima observed in transition series?
A
Near the middle of each transition metal series.
15
Q
What does very high enthalpy of atomisation indicate?
A
Nobility or low reactivity of the metal.
16
Q
Which transition series has greater enthalpy of atomisation — first second or third?
A
5d>4d>3d
17
Q
What is lanthanoid contraction?
A
Regular decrease in atomic radii caused by filling of 4f orbitals before 5d.
18
Q
What is the effect of lanthanoid contraction on Zr and Hf radii?
A
They have almost identical radii (Zr 160 pm Hf 159 pm).
19
Q
What causes lanthanoid contraction?
A
Imperfect shielding of electrons within the same f orbitals.
The filling of 4f orbital before 5dorbitals
20
Q
Why do transition metals show high enthalpies of atomisation?
A
Due to large number of unpaired electrons producing strong interatomic bonding.
21
Q
Why is oxidation state greater than +2 difficult in Cu Ni and Zn?
A
Because of their high third ionisation enthalpies.
22
Q
Which 3d element shows the largest number of oxidation states and why?
A
Manganese because it can use all five d orbitals giving oxidation states differing by unity.
23
Q
How do oxidation states vary across d-block compared to p-block?
A
In d-block higher oxidation states are more stable for heavier elements (opposite of inert pair effect).
24
Q
Why are Mo(VI) and W(VI) more stable than Cr(VI)?
A
Due to greater stabilisation in heavier elements—Cr(VI) acts as strong oxidising agent in acidic dichromate.
25
When are low oxidation states stabilised in complexes?
When ligands possess π-acceptor character along with σ-bonding.
26
Which transition element does not show variable oxidation states?
Scandium (Z = 21).
27
Why is Cu unable to liberate hydrogen from acids?
Because Cu has positive E° value and high energy required to convert Cu(s) to Cu2+(aq) is not compensated by hydration enthalpy.
28
Which acids react with copper?
Only oxidising acids such as nitric acid and hot concentrated sulphuric acid.
29
Why is E°(Cu2+/Cu) = +0.34 V positive?
Due to high atomisation enthalpy and low hydration enthalpy of Cu.
30
Why is Cr2+ a reducing agent while Mn3+ is oxidising though both are d4?
Cr2+ → Cr3+ forms stable half-filled t2g3; Mn3+ → Mn2+ forms more stable d5.
31
Which ions are strong reducing agents among first-row transition metals?
Ti2+ V2+ Cr2+.
32
Which ions are strong oxidising agents in aqueous solution?
Mn3+ and Co3+.
33
Why are some E° values of Mn Ni and Zn more negative than trend?
Due to extra stability of their associated oxidation states.
34
What is the highest oxidation state in Ti V and Cr halides?
TiX4 VF5 CrF6.
35
Is Mn(+VII) represented in simple halides?
No but MnO3F exists.
36
Which metals form trihalides beyond Mn?
Only FeX3 and CoF3.
37
Why does fluorine stabilise highest oxidation states?
Because of high lattice energy and strong bond enthalpy.
38
Why are low-oxidation fluorides unstable (e.g. VX2)?
Because fluorine strongly stabilises higher oxidation states.
39
Which Cu halides exist?
Cu(II) halides exist but CuI is unstable in aqueous solution and disproportionates.
40
Why is Cu2+(aq) more stable than Cu+(aq)?
Because Cu2+ has much more negative hydration enthalpy.
41
Which element stabilises highest oxidation state better — oxygen or fluorine?
Oxygen stabilises highest oxidation states more effectively.
42
What is the highest oxidation state in oxides of first-row transition metals?
Equal to group number from Sc2O3 to Mn2O7.
43
Are higher oxides of Fe above Fe2O3 known?
No except ferrates(VI) in alkaline medium which decompose.
44
What are oxocations?
Cations containing oxygen such as VO2+ VO2+ (VIV) TiO2+.
45
Why is Mn2O7 covalent?
Because at high oxidation state ionic character decreases giving covalent green oil Mn2O7.
46
What shape surrounds Mn in Mn2O7?
Each Mn is tetrahedrally surrounded by oxygen with Mn-O-Mn bridge.
47
Which tetrahedral oxoanions are known?
[MO4]n− for VV CrVI MnV MnVI MnVII.
48
Why does oxidising power increase VO2+ < Cr2O72− < MnO4−?
Because stability of reduced species increases along series.
49
Which metals are passive to dilute non-oxidising acids?
Titanium and vanadium.
50
What are magnetic behaviours of substances?
Diamagnetic = repelled paramagnetic = attracted ferromagnetic = strongly attracted.
51
What determines magnetic moment in first-row transition metal compounds?
Number of unpaired electrons using spin-only formula √(n(n+2)).
52
What causes colour in transition metal ions?
d-d electron transition between split d orbitals absorbing visible light.
53
What affects frequency of absorbed light in transition metals?
Nature of ligand and crystal field splitting.
54
Why do transition metals show high catalytic activity?
Because they can change oxidation states and form complexes on surfaces.
55
Example catalytic cycle involving Fe3+ persulphate and iodide
2Fe3+ + 2I− → 2Fe2+ + I2 THEN 2Fe2+ + S2O82− → 2Fe3+ + 2SO42−.
56
What are interstitial compounds?
Compounds where small atoms (H C N) occupy metal lattice voids e.g. TiC Mn4N Fe3H.
57
What properties do interstitial compounds show?
High melting point hardness metallic conductivity chemical inertness.
58
Give examples of important ferrous alloys
Alloys with Cr V W Mo Mn producing steels and stainless steels; brass = Cu-Zn bronze = Cu-Sn.
59
Do all transition metals form MO oxides?
All except scandium form ionic MO oxides.
60
How does basic character vary with oxidation state in transition metal oxides?
As oxidation number increases ionic character decreases and acidic character increases.
61
What does Mn2O7 produce in water?
HMnO4 (permanganic acid).
62
What does CrO3 produce in water?
H2CrO4 and H2Cr2O7.
63
V2O5 nature and forms ?
It is mainly acidic but amphoteric and forms VO43− and VO2+ salts.
64
Sequence of vanadium oxide basicity
V2O3 basic → V2O4 less basic → V2O5 amphoteric.
65
What is chromite ore formula?
FeCr2O4.
66
How is sodium chromate obtained from chromite?
Fusion with alkali and oxidation followed by extraction.
67
Write conversion of chromate to dichromate
2CrO42− + 2H+ → Cr2O72− + H2O.
68
Write conversion of dichromate to chromate
Cr2O72− + 2OH− → 2CrO42− + H2O.
69
Which is more soluble — sodium or potassium dichromate?
Sodium dichromate is more soluble.
70
How is potassium dichromate prepared?
Treat sodium dichromate solution with KCl to crystallise K2Cr2O7.
71
What is oxidation state of Cr in chromate and dichromate?
+6 in both ions.
72
Describe structure of chromate ion
Tetrahedral XO42−.
73
Describe structure of dichromate ion
Two tetrahedra sharing one corner via Cr-O-Cr bridge.
74
Are dichromates strong oxidising agents?
Yes especially in acidic solution.
75
Half-reaction for dichromate reduction in acid
Cr2O72− + 14H+ + 6e− → 2Cr3+ + 7H2O.
76
List species oxidised by acidified dichromate
I− to I2; Fe2+ to Fe3+; Sn2+ to Sn4+; sulphides to sulphur.
77
How is potassium permanganate prepared (fusion route)?
MnO2 + KOH + O2 → K2MnO4 → disproportionation → KMnO4.
78
Write disproportionation of manganate
3MnO42− + 4H+ → 2MnO4− + MnO2 + 2H2O.
79
What happens when KMnO4 is heated?
2KMnO4 → K2MnO4 + MnO2 + O2.
80
What is the colour and magnetism of manganate?
Green and paramagnetic (one unpaired electron).
81
What is the colour and magnetism of permanganate?
Purple and diamagnetic (no unpaired electrons).
82
Write KMnO4 reaction with iodide in acid
10I− + 2MnO4− + 16H+ → 2Mn2+ + 8H2O + 5I2.
83
Write KMnO4 oxidation of Fe2+ in acid
5Fe2+ + MnO4− + 8H+ → Mn2+ + 4H2O + 5Fe3+.
84
Write KMnO4 oxidation of oxalate in acid
5C2O42− + 2MnO4− + 16H+ → 2Mn2+ + 10CO2 + 8H2O.
85
Write KMnO4 oxidation of nitrite in acid
5NO2− + 2MnO4− + 6H+ → 2Mn2+ + 5NO3− + 3H2O.
86
Write KMnO4 oxidation of H2S in acid
5S2− + 2MnO4− + 16H+ → 2Mn2+ + 8H2O + 5S.
87
Write KMnO4 reaction with iodide in neutral/alkaline medium
2MnO4− + H2O + I− → 2MnO2 + 2OH− + IO3−.
88
Write KMnO4 oxidation of thiosulphate
8MnO4− + 3S2O32− + H2O → 8MnO2 + 6SO42− + 2OH−.
89
Why should KMnO4 titrations not be done in HCl?
Because HCl is oxidised to chlorine gas.
90
What are major industrial uses of KMnO4?
Oxidant bleaching and decolourisation of fibres and oils.
91
List the oxidation states of Sc, Ti and V.
Sc: +3\nTi: +2, +3, +4\nV: +2, +3, +4, +5
92
List the oxidation states of Cr and Mn.
Cr: +2, +3, +4, +5, +6\nMn: +2, +3, +4, +5, +6, +7
93
List the oxidation states of Fe and Co.
Fe: +2, +3, +4, +6\nCo: +2, +3, +4
94
List the oxidation states of Ni and Cu.
Ni: +2, +3, +4\nCu: +1, +2
95
List the oxidation states of Zn.
Zn: +2
96
Density:
Sc < Ti < V < Zn < Cr < Mn < Fe < Co < Ni ≈ Cu
97
Ionisation enthalpy (IE₁):
Sc < V < Cr < Ti < Mn < Ni < Cu < Co < Fe < Zn
98
M⁰ atomic radius (size):
Co ≈ Ni < Fe < Cu < Cr < V < Mn ≈ Zn < Ti < Sc
99
Enthalpy of atomisation (ΔₐH°):
Zn < Mn < Sc < Cu < Cr < Fe < Co < Ni < Ti < V
100
Enot value same for
V and Mn
101
Max and min atomisation enthalpy
V max : Zn min
102
Lanthanoid contraction effect
Cumulative contraction across lanthanoids causes 3d and 4d transition metals to have similar radii
103
Zr vs Hf radii
Zr 160 pm and Hf 159 pm have almost identical radii due to lanthanoid contraction
104
Ce4+ stability reason
Formation of Ce4+ is favoured because Ce4+ has noble gas configuration
105
Ce4+ oxidising behaviour
Ce4+ is a strong oxidant and readily reverts to the common +3 oxidation state
106
Analytical use of Ce4+
Ce4+ is used as a good analytical reagent in redox titrations
107
Elements showing +4 oxidation state
Pr, Nd, Tb and Dy show +4 oxidation state but only in oxides
108
Eu2+ property
Eu2+ is a strong reducing agent and converts to the common +3 state
109
Samarium oxidation behaviour
Samarium behaves like europium and shows both +2 and +3 oxidation states
110
Physical nature of lanthanoids
Lanthanoids are silvery white soft metals and tarnish rapidly in air
111
Hardness trend in lanthanoids
Hardness increases with atomic number; samarium becomes steel hard
112
Melting point of samarium
Samarium melts at 1623 K
113
Lanthanoids conductivity
Lanthanoids are good conductors of heat and electricity
114
Density trend exception
Density and other properties change smoothly except for Eu, Yb and sometimes Sm, Tm
115
Colour of La3+ and Lu3+
La3+ and Lu3+ ions are colourless; others show colour
116
f0 and f14 type ions
La3+ and Ce4+ are f0 type; Yb2+ and Lu3+ are f14 type
117
Ionisation enthalpy trend
First IE ~600 kJ/mol, second IE ~1200 kJ/mol comparable to calcium
118
Low third ionisation enthalpy
Lanthanum, gadolinium and lutetium have low third ionisation enthalpy
119
Reactivity trend in lanthanoids
Early lanthanoids are highly reactive like calcium; later ones behave like aluminium
120
Carbide formation in lanthanoids
Lanthanoids form carbides Ln3C, Ln2C3 and LnC2 on heating with carbon
121
Carbide formation reaction
Ln + C (on heating) → Ln3C / Ln2C3 / LnC2
122
Use of lanthanoids in alloys
Lanthanoids are used to produce alloy steels for plates and pipes
123
Mischmetall composition
Mischmetall contains ~95% lanthanoid metals, ~5% iron with traces of S, C, Ca, Al
124
Uses of mischmetall
Mischmetall is used in Mg-based alloys to make bullets, shells and lighter flints
125
Lanthanoid oxides as catalysts
Mixed lanthanoid oxides are used in petroleum cracking as catalysts
126
Ln oxides as phosphors
Individual lanthanoid oxides are used as phosphors in TV screens and fluorescent surfaces
127
Actinoids radioactivity
Actinoids are radioactive elements
128
Appearance of actinoid metals
Actinoid metals are silvery in appearance
129
Reactivity of actinoids
Actinoids are highly reactive especially in finely divided state
130
Actinoids with boiling water reaction
Boiling water forms a mixture of oxide and hydride with actinoids
131
Actinoid water reaction example
An + H2O (hot) → AnO2 + AnH2 (mixture of oxide and hydride)
132
Action of HCl on actinoids
Hydrochloric acid attacks all actinoid metals
133
Action of HNO3 on actinoids
Nitric acid slightly attacks actinoids due to formation of a protective oxide layer
134
Action of alkali on actinoids
Alkalies have no action on actinoids
135
Actinoid ionisation enthalpy
Early actinoids have lower ionisation enthalpies than early lanthanoids
136
Importance of lanthanoid contraction
Lanthanoid contraction is more important as chemistry after actinoids is less known
137
TiO industrial use
TiO is used in pigment industry
138
MnO2 industrial use
MnO2 is used in dry battery cells
139
Battery metals requirement
Battery industry requires Zn and Ni/Cd systems
140
Coinage metals group
Group 11 elements are called coinage metals
141
UK copper coins
UK copper coins are copper-coated steel
142
UK silver coins
UK silver coins are Cu/Ni alloy
143
V2O5 catalytic role
V2O5 catalyses oxidation of SO2 in manufacture of sulphuric acid
144
SO2 oxidation reaction using V2O5
2 SO2 + O2 → 2 SO3 (catalyst V2O5)
145
Ziegler catalyst reaction base
TiCl4 with Al(CH3)3 forms Ziegler catalysts for polyethylene production
146
Polyethylene formation reaction
TiCl4 + Al(CH3)3 → Ziegler catalyst → polymerisation of ethene to polyethylene
147
Iron catalyst use
Iron catalyst is used in Haber process for ammonia synthesis
148
Haber process reaction
N2 + 3 H2 → 2 NH3 (catalyst Fe)
149
Nickel catalyst application
Nickel catalyst is used for hydrogenation of fats
150
Hydrogenation reaction example
R-CH=CH-R + H2 → R-CH2-CH2-R (catalyst Ni)
151
Wacker process catalysis
Oxidation of ethyne to ethanal is catalysed by PdCl2
152
Wacker process reaction
HC≡CH + H2O + PdCl2 → CH3CHO + Pd + HCl
153
Nickel complexes application
Nickel complexes help polymerisation of alkynes and aromatic compounds
154
Photographic role of AgBr
AgBr is used in photography due to its light-sensitive properties
155
+4 oxdn state lathanoids only shown by
ce nd pr tb dy
156
highest oxdn state lathanoids
plutonium neptunium
157
which element shows no +3 actinoid
thorium
158
Lanthanide + O2
Ln + O2 → Ln2O3
159
Lanthanide + H2O
Ln + 3 H2O → Ln(OH)3 + 3/2 H2
160
Lanthanide + Halogens
Ln + 3 X2 → 2 LnX3
161
Lanthanide + Sulfur (on heating)
2 Ln + 3 S → Ln2S3
162
Lanthanide + Nitrogen (on heating)
2 Ln + N2 → 2 LnN
163
Lanthanide + Carbon (at 2773 K)
Ln + 2 C → LnC2
164
Lanthanide + Acids
Ln + 6 HCl → 2 LnCl3 + 3 H2
165
Lanthanide + Hydrogen
Ln + H2 → (usually forms hydrides LnH2 / LnH3)
166
Name all the carbides form from Ln
Ln3C1:Ln2C3:Ln1C2
Erwin Smith
flashcards
Decks in class (16)
# Cards
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Qualitative Quantitative Analysis Kjhedahl26
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OC Tests57
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Titration, Indicator, Redox52
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Salt Analysis107
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Purification69
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Modern Physics Final108
-
Thermodynamics Final56
-
Semiconductor Flashcards44
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Battery And Corrosion62
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P Block 1291
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P Block 11169
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DF block166
-
Name Reactions54
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Heat New57
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Biomolecules 🧬63
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