D And F Block Elements Flashcards by Dr Menaka Raut

The d-block of the periodic table contains the elements of the groups………… in which the d orbitals are progressively filled in each of the four long periods.

3-12

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……../……../……… of group 12 have full d10 configuration in their ground state as well as in their common oxidation states and hence, are not regarded as transition metals

Zinc, cadmium and mercury

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Statement 1: The enthalpy of atomisation is an important factor in determining the standard electrode potential of a metals.
Statement 2: The metals with very high enthalpy of atomisation (i.e., very high boiling point) tend to be noble in their reactions (see later for electrode potentials).

Botha are correct

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Assertion: There is a maxima in atomisation energy at about the middle of each series

True Reason:One unpaired electron per d orbital is particularly favourable for strong interatomic interaction

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This catalytic activity of d block elements is ascribed to their (2) abilities

adopt multiple oxidation states and to form complexes.

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Vanadium (V) oxide is used in

Contact process

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Finely divided iron is used in

Habers process

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Nickel is used in

Catalytic hydrogenation

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In wackers process catalyst used is

PdCl2

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Brass

Cu 60% and Zn 40%

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German silver

Cu(1) + Zn (1) + Ni (2)

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Bronze

Cu and Sn

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The transition metals form a large number of complex compounds. This is due to
(3) reasons

comparatively smaller sizes of the metal ions
their high ionic charges
availability of d orbitals for bond formation.

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The colour observed corresponds to the complementary colour of the light absorbed

True

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V+4 ion is ……… in colour

Blue

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Alloys may be………. solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other

homogeneous

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The alloys are formed by atoms with metallic radii that are within about……… percent of each other

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The alloys so formed are hard and have often high…….

melting points

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Various steel and stainless steel alloys are from which elements

Chromium
Vanadium
Tungsten
Molybdenum
Manganese

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Best known alloys are of

Ferrous alloys

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The best known ferrous alloys are blender]d with previous elements to obtain steels and stainless steels

True

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Alloys of transition metals with non transition metals
(2)

Brass: Cu/Zn
Bronze: Cu/Sn

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Interstitial compounds are those which are formed when small atoms like…./…/… are trapped inside the crystal lattices of metals.

H
C
N

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Write some interstitial compounds
(5)

TiC
Mn4N
Fe3H
VH0.56
TiH1.7

The principal physical and chemical characteristics of interstitial compounds are (6)

They have high melting points, higher than those of pure metals. They are very hard, some borides approach diamond in hardness. They retain metallic conductivity. They are chemically inert. Neither ionic nor covalent Hardness of NiB is close to the diamond

The elements which give the greatest number of oxidation states occur in or near the middle of the series

True

The lesser number of oxidation states at the extreme ends stems from 2 reasons

either too few electrons to lose or share (Sc, Ti) or too many d electrons (hence fewer orbitals available in which to share electrons with others) for higher valence (Cu, Zn).

Assertion: The EƟ values for M2+/M indicate a decreasing tendency to form divalent cations across the series. Reason: This general trend towards less negative EƟ values is related to the increase in the sum of the first and second ionisation enthalpies.

Correct and correct explanation

Why are EƟ M2+/M values for Mn, Ni and Zn are more negative than expected from the general trend.

For Mn the stability of Mn+2 as d5 configuration For Zn it is d10 configuration in Zn+2 state For Ni it is the high negative value of enthalpy of hydration

Copper can’t liberate H2 gas by reacting with acids

EƟ value M2+/M for Copper is +ve thus the oxidation reaction of Cu to Cu+2 will not take place and opposite reaction is favoured thus Cu is more stable than Cu+2 Since the Cu will not release electrons the H+ will not get any electrons thus not liberation of H2 gas

Copper can be oxidised to Cu+2 in reaction with (2) acids

Conc. H2SO4 Conc. HNO3

Copper reaction with nitric acid

Cu + HNO3 ————> Cu(NO3)2 + NO2 (g) Here copper nitrate is formed with BROWN gas NO2

Reaction of copper with sulphuric acid

Cu + H2SO4 ————> CuSO4 + SO2 (g)

Which is stronger reducing agent Cr+2 or Fe+2

Cr+2 Because E* Cr+3/Cr+2 is -ve while for Fe it is +ve

Which stronger Oxidising agent Mn+3 or Co+3

Co+3 As E* M+3/M+2 for Co is more positive than that for Mn

General characteristics of lanthanoid elements

All the lanthanoids are silvery white soft metals They tarnish rapidly in air. The hardness increases with increasing atomic number, samarium being steel hard. Their melting points range between 1000 to 1200 K but samarium melts at 1623 K. They have typical metallic structure and are good conductors of heat and electricity. Density and other properties change smoothly except for Eu and Yb and occasionally for Sm and Tm. Many trivalent lanthanoid ions are coloured both in the solid state and in aqueous solutions except La3+ Lu3+ ion

The hydroxides of ‘Ln’ are just hydrated oxides

False The hydroxides are definite compounds, not just hydrated oxides

The best single use of the lanthanoids is for the production of…….

alloy steels These are used in plates and pipes

A well known alloy is mischmetall which consists of a (2) major constituents and some (4) in trace amounts

Lanthanoid metal (~ 95%) Iron (~ 5%) Traces of S, C, Ca and Al.

A good deal of mischmetall is used in……….. -based alloy to produce bullets, shell and lighter flint.

Mg Magnesium

The lanthanoid metals in mischmetall are

Lanthanoid metals constitute 95% Cerium [Ce] 55% Lanthanum [La] 25% Neodymium [Nd] ~18%

The actinoids are radioactive elements and the earlier members have relatively……… half-lives

long

The later Actinoids have half life period ranging from day to minute

True

Lawrencium (103) has half life of

3 mins

Iron and steel production is based on (3) things

Reduction of iron oxides Removal of impurities Addition of carbon and alloying metals such as Cr, Mn and Ni.

TiO is used in

Pigment industry

MnO2 is used in

Dry cell battery

The elements of Group 11 are being called the…….. metals

coinage

UK copper coins are

Copper coated steel

Silver uk coins are

Cu and Ni alloy

The photographic industry relies on the special light-sensitive properties of…….

AgBr

Various precious metals such as……/…../….. and industrially important metals like…../…../….. belong to the transition metals series.

silver, gold and platinum iron, copper and titanium

Nearly all the transition elements display typical metallic properties such as (6)

High tensile strength Ductility Malleability High thermal and electrical conductivity Metallic lustre.

E* Cu+2/Cu is positive why?

Its atomisation energy and first 2 ionisation energies cumulatively are highly positive and the hydration energy is less negative to compensate it thus the E* becomes +ve

Why is Cr+2 reducing though it had d4 configuration and it can get reduced itself to d5

It self oxidises itself and becomes in d3 as in d3 configuration as studied in CFST it has t2g (3) eg (0) increasing symmetrical thus stable instead of d5

Why is Mn+3 oxidising agent while it can give one more electron to attain stability as we saw in Cr+2

In case of Mn it has greater stability in d5 thus it gains an electron and becomes in d5 highly stable half filled

Permanganate titrations in presence of hydrochloric acid are unsatisfactory since hydrochloric acid is……….. to chlorine.

oxidised

Low oxidation states are found when a complex compound has ligands capable of π-acceptor character in addition to the σ-bonding

Metals in lower oxidation state are stabilised by the "pie" acid ligands Through: Coordination compounds/ Synergic bonding/ pie acceptor or non classical ligands Example: Ni(CO)4 and Fe(CO)5, the oxidation state of nickel and iron is zero.