d and f block

why does d block elements shows variable oxidation state

because the energy difference between (n-1)d and ns orbital is very less .hence the electrons in (n-1) orbitals as well as in ns orbitals take participation in bond formation

which transition element in 3d series exhibits the most variable oxidation state

mn( manganese ) , due to maximum no. of unpaired electrons

which electrons are stable in d orbitals

d0

d3

d5

d10

why mn+2 is more stable than fe+2

configuration of mn+2 -- (ar) 3d54s0

configuration of fe+2 -- (ar) 3d64s0

hence by this we can see that d5 is more stable than d6

what is the most stable orbital of cobalt

d6 ( because t2g is fully filled )

what is the most stable orbital of chromium

d3 (because t2g becomes half filled)

which elements can oxidize the metals to their highest oxidation state why?

oxygen and fluorine

due to their small size and high value of electronegativity

out of oxygen and Florine which helps the transitions mentals to show higher value of oxidation

with oxygen

because oxygen can form multiple bond while fluorine can form single bond only

what is the color of dichromate ion

orange

what is the color of chromate ion

yellow

what are the steps required for the preparation of potassium dichromate from chromite ore

conversion of chromite ore to sodium chromate

conversion of sodium chromite into sodium dichromate

conversion of sodium dichromate into potassium dichromate

chromate and dichromate are colored due to

ligand to metal charge transfer

the colour of kmn04 is due to

ligand to metal charge transfer

between lanthanoids and actinoids - which is more reative

actinoids

why actinoids show greater number of oxidation state

due to comparable energies of 5f, 6d and 7s orbitals. Hence, all their electrons can take part in bond formation.

the transition elements generally form coloured compounds due to

due to presence of unpaired electrons and d-d transition

transition elements have high enthalpy of atomization

because of large no. of unpaired electrons in their atoms the have strong interatomic interaction and hence stronger metallic bonding b/w atoms resulting in higher enthalpy of atomization

why transition element are good catalyst

due to their ability to form multiple oxidation state and to form complexes and they have large surface area

what are interstitial compounds

interstitial compounds are those compounds which are formed when small atoms like H,C,N are trapped inside the crystal lattice of metals .

ex- TiC , Mn4N

are interstitial compounds ionic or covalent

they are neither covalent nor ionic

what are the properties of interstitial compound

they are chemically inert

they retain metallic conductivity

they have higher melting point than those of the pure metals

they are very hard

what is meant by disproportion

disproportion reaction involve the oxidation and reduction of the same substance

explain why cu+ ion is not stable in aqueous solution

• cu+ in aqueous solution undergo disproportion to give cu2+ and cu

• energy is required to remove one electron from Cu+ to Cu2+ but high hydration energy of Cu2+ compensates for it and thus Cu+ ion in an aqueous solution is unstable

how does the potassium acidified permanganate solution react with iron , so2, oxalic acid

what is the formula of potassium dichromate

k2Cr2O7

what is the color of cromate ion

yellow

what is the color of dichromate ion

orange

chromate ion is stable in?

basic medium

dicromate ion is stable in

acidic medium

what is the formula of chromite ore

FeCr2O7

what is potassium dichromate used as

it ia used as a primary standard in volumetric analysis

what is the oxidation state of lanthanoids

+3 only

what happens when lanthanoids are heated in gas

they combine with hydrogen

what is the cause of lanthanoid contraction

greater effect of increased nuclear charge that screening effect

which type of elements in lanthanoids show +2 and +4 oxidation state

when f subshell is half filled,fully filled or empty

which element have +4 oxidation state

ce and tb

are ce and tb good oxidizing agent or reducing agent

oxidizing agent

which element in lanthanoids show +2

eu and Yb( they are strong reducing agent )

Eu is half filled

Yb is fully filled f subshell

what does lanthanoid contraction do

decrease both the atomic radii and ionic radii

all the d block elements show negative electrode potential except?

copper

why does copper show positive electrode potential

due to inability to liberate h2 from acids