D and F Block

What are transition metals?

Metals which have incomplete d subshell in neutral atom or any of its ions

Why Zn,Cd and Hg are not regarded as transition elements?

Because they have full d10 configuration in their ground state and common oxidation state

Electronic configuration of the outermost orbital of transition elements

(n-1)d1-10 ns1-2

Energy difference between (n-1)d and ns is

little

Which elements have more than one metallic structure at room temperature?

Zn, Cd, Hg, Mn

Why transition elements have high melting and boiling points?

Greater involvement of (n-1)d electrons in addition to ns electrons

The maxima at the middle of the mp graph indicates that

One unpaired electron per d orbital is particularly more stable for stronger interactions.

The enthalpies of atomisation is higher for second and third series than

first

High enthalpy of atomisation means

High boiling point

What is lanthanoid contraction?

The filling of 4f orbital before the 5d orbital results in a general decrease in atomic radii

Net result of lanthanoid contraction is that

Second and third d series exhibit similar radii and similar physical and chemical properties

Which two elements have similar atomic radii of 159 pm?

Zr and Hf

Factor responsible for lanthanoid contraction

The imperfect shielding of one electron by the other in the same orbital

Shielding of f is fairly lower than

d

Which element in d block has the lowest density?

Sc

Which elements have the highest density?

Os and Ir

Why atomic radii generally decrease in 3d series till Co?

Increasing effective nuclear charge

Why around Co the atomic radii is slight increasing?

Increasing electron electron repulsion

What are the three terms responsible for the ionisation enthaply?

Attraction of electrons towards nucleus, electron electron repulsion, exchange energy

Exchange energy is responsible for the stabilisation of

Energy states

Exchange energy is directly proportional to the no. of

Parallel spins and exchange pairs

Why is it difficult to obtain greater than +2 os for Co, Ni and Zn

High third ionisation enthalpy

The variability of os is because of

Incomplete filling of d orbitals

In p block lower os are favoured by

Heavier elements

In d block lower os are favoured by

Lighter elements

π-acceptor ligands stabilize low oxidation states

Because they take up electron density from the metal

Transition metals show variable O.S. due to

the involvement of both (n-1)d and ns electrons and small energy difference between ns and (n-1)d orbitals

What is the reason behind Cu’s inability to liberate H2 gas from acids?

Positive electrode potential

What acids react with Cu?

HNO3 and hot conc H2SO4

What is the reason for the positive electrode potential of Cu?

The energy required for transformation from Cu(s) to Cu(aq) is not compensated by its hydration enthalpy

The general trend of less negative electron potential is related to the

Increase in the sum of the first and the second ionisation enthalpies

Why Mn and Zn has more -ve E than expected?

Stable configuration

Why the E for Ni is -ve than expected?

High hydration enthalpy

Beyond Mn no metal has trihalides except?

Fe and Co

Why the ability of F to stabilise high os in case of Cof3 is high?

High lattice energy

Why the ability of F to stabilise high os in case of VF5 and CrF5 is high

High bond enthalpy

Fluorides in lower os are

unstable

All Cu 2 halides are known except

I

Cu(II) compounds are unstable in aq solution and undergoes

Disproportionation

Cu+ or Cu2+ which is more stable?

Cu2+

Why Cu2+ is much more stable than Cu+?

High hydration enthalpy that compensates for the second ionisation energy

Why the ability of O to stabilise higher os is higher than F?

Ability to form multiple bonds

In Mn2O7 each O surround the Mn

Tetrahedrally

Strongest oxidising agents in +3 state are

Mn and Co

Strongest reducing agents in +2 state are

Ti, V and Cr

The irregularity in the E(M2+/M) can be explained by irregular variation of

Ionisation and sublimation enthalpies

Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

High electronegativity

What substances are repelled by magnetic field?

Diamagnetic

What substances are attracted by magnetic field?

Paramagnetic

Colour of Ti3+

Purple

Colour of V4+

Blue

Colour of V3+

Green

Colour of V2+

Violet

Colour of Cr3+

Violet

Colour of Mn3+

Violet

Colour of Cr2+

Blue

Colour of Mn2+

Pink

Colour of Fe2+

Green

Colour of Fe3+

Yellow

Colour of Co2+

Blue pink

Colour of Co3+

Blue pink

Colour of Ni2+

Green

Colour of Cu2+

Blue

Why do transition metals form a large number of complexes?

Smaller size of metal ions, high ionic charges and availability of d orbitals

Why transition elements show catalytic properties?

Ability to adopt multiple os and to form complexes

Vanadium oxide is used in

Contact process

Finely divided iron is used in

Haber’s process

Nickel is used as a catalyst in

Hydrogenation

Why are transition elements able to form interstitial compounds?

the lattice of transition metals contains open spaces that can be filled with atoms such as H, C, and N.

Interstitial compounds have ——— melting points

High

T/F: Interstitial compounds are very hard

T

T/F: Interstitial compounds do not retain metallic conductivity

F

Interstitial compounds are chemically ———

inert

Why do transition elements form alloys?

Because of similar size

Ferrous alloys are used for the production of

Steel and Stainless steel

Cu and Zn gives the alloy

Brass

Cu and Sn gives the alloy

Bronze

All metals except Sc form —— oxides

Ionic

Os increases, ionic character —————-

Decreases

Mn2O7 is what colour oil

Green

V2O5 is amphoteric but mainly

Acidic

V2O3 is

Basic

CrO is

Basic

Cr2O3 is

Amphoteric

Which is one of the most imp chemical used in leather industry as an oxidant?

Potassium Dichromate

K2Cr2O7 is obtained from which ore

Chromite ore (FeCr2O4)

What is the structure of chromate ion?

Tetrahedral

What is the structure of dichromate ion?

Cr-O-Cr bridge

Potassium Permangante is prepared from which ore?

Pyrolusite (MnO2)

What is the colour of KMnO4?

Purple

What is the colour of K2MnO4?

Green

Manganate is what kind of magnetic material?

Paramagnetic

Potassium Permanganate is isostructural with

KCLO4

Permanganate is what kind of magnetic material?

Diamagnetic

Despite having no unpaired electrons K2Cr2O7 and KMnO4 exhibit colour because of

Ligand to metal charge transfer

Potassium Permanganate on heating produces

K2MnO4 and MnO2

f - block consists of lanthanoids and actinoids of how many elements each

14

The lanthanoids have how many stable os?

One