D And F Notes 1

Question 1

Name. A compound in which the metals oxidation state is same as its group number

Answer 1

KMnO4 here Mn is 7+ and it’s under VII B also K2Cr2O7 or K2Cr2O4 here Cr is 6+ and it is under VI B

Question 2

Why do exceptions exist

Answer 2

This is due to symmetry, nucleus electron and electron - electron forces which give stability.

Question 3

Why are transition metals important

Answer 3

• Except mercury (liquid) all the others are solid metals such as strategic, noble, coinage metals.
• Some of the compounds are very important in both in industries and laboratories.
• They both show variable oxidation state.

Question 4

The highest fluoride is MnF4 but highest oxide is Mn2O7give reason.

Answer 4

Oxygen has the ability to form p pi-d pi multiple bonding with the manganese and stabilize the oxide.

• in the lower os metals lose electrons and ionic bonds are formed whereas in higher oxidation state metals sate , metals share their valence electrons ans form covalent bonds.
• in the transition elements, the successive oxidation state differ by 1
• elements in the middle of the series exhibit maximum possible oxidation states. Mn is till +7 and Ossining till +8.

Question 5

Cu2I2 is more stable than CuI2. Give reason

Answer 5

I- is. Powerful reducing agent, it reduces Cu2+ to Cu+ and itself gets oxidized from I- to I2

2 u2+. +. 4I- —-> I2+. + Cu2I2 (s)

Question 6

Why are transition metals the best catalyst?

Answer 6

V2O5 in contact process Iron in Habers process with molybdenum as the promoter, platinum in Oswald’s process and Ni, Co in hydrogenation of oil are the best catalysts along with Co and Th for petrol preparation.

• Due to the unpaired d electron , they have the capacity to remit and absorb energy, thus they are able to provide être required Ea that is the minimum energy required by reactant.
• In some cases the transition elements form intermediate compounds. These intermediates decompose easily to products and provide an alternate path with lower Ea.
• the and with reactants absorbing energy.
• due to their ability to give alternate mechanism.
  (In notes)

Question 7

Why KMnO4 is purple and K2Cr2O7is orange colour. And K2Cr2O4is yellow colour.

Answer 7

1. Here the transition metal ions Mn+7 and Cr+6 are just argon electron configurations. There is no unpaired d electron. So their colour is not due to the d-d transition.
2. The colour is due to the charge transfer that is the electron transfer from the oxygen to the empty d’orbital of Mn, Cr. This is a momentary transfer.

Question 8

Why metal in the lower oxidation state form basic oxides and higher oxidation states give acidic oxide.

Answer 8

In lower oxidation state, the metal ion has the tendency to loose electrons and the oxides ads formed by ionic bond and hence they are basic in nature . While in the higher os, when it’s os is maximum, the ionic size is very small, the metal has no tendency to loose electron ans oxides are formed by sharing electron hence they are acidic in nature.

Question 9

Lanthanides have very limited os

Answer 9

Because orbital electrons are difficult to take apart in bonding due to complex nature of the f orbital.