d Block Flashcards
What groups does it contain?
Gp 3 to 12
Which elements are not typical transition elements?
Zn,Cd and Hg
D shell sequence for all four periods
- 1 2 3 5 5 6 7 8 10 10
- 1 2 4 5 6 7 8 10 10 10
- 1 2 3 4 5 6 7 9 10 10
- 1 2 3 4 5 6 7 8 10 10
Which elements have greater ionisation enthalpies?
The 2nd and 3rd series have greater atomisation enthalpies than the 1st series
4d and 5d elements are of nearly the same size … why?
This is because of poor shielding of 4f electrons.
what is the general trend in density?
It increases.
Which three elements have a density less than 5gm/cm^3
Sc,Ti and Y
General trend in ionisation enthalpy?
It increases along a series.
What is the cause for the irregularity in the 1st ionisation enthalpy of the 3d elements?
Removal of one electron alters the energies of the 4s and 3d orbitals and there is some energy reorganisation etc.
Why is the ionisation enthalpy of chromium lower than it’s supposed to be?
This is because it doesn’t suffer any change in its d configuration.
Why is the IE of Zn higher?
This is because it represents an ionisation from 4s level.
What is required to form the +2 oxidation state?
- The sum of the 1st and 2nd IE
* The enthalpy of atomisation
+2 is the lowest oxidation state for all 3d elements except …?
Sc and Cu
Which series has the higher ionisation enthalpies. 4d or 5d .. and why?
5d, because of lanthanoid contraction
Which elements have the highest and lowest IE?
Highest- Hg
Lowest- La
Which element exhibits the greatest no. of oxidation states?
Mn
Elements with a greater no. of oxidation states occur where in the d block.
towards the middle
Which element doesn’t exhibit the +2 ox.state?
Sc
Higher ox.states become less stable as we move from….
The middle of the block to the peripheries.
How is change in ox.state of other elements is different from change in oxidation state in transition metals.
In transition metals, ox.states usually vary by unity, whereas , in other elements, it varies by 2.
Mixed oxide are formed by which elements?
Mn- Mn304
Fe-Fe304
Co-Co3o4
Which transition element does not exhibit variable oxidation states?
Sc
What determines maximum oxidation states?
sum of the s and d electrons
What is the reason for the irregularity in the E- values in the 3d series?
The irregularity in the ionisation enthalpies
which ox.state is of little importance to Mn?
+3
E- values for Ni is related to its …
highest hydration enthalpy
Which halides are more stable with higher ox.states and which with lower ones?
Cl and F - higher
I - Lower
Which is more stable in aq. solution. Cu2+ or Cu+?
Cu2+ is more stable in aq. medium because of its higher hydration enthalpy which compensates for its IE2.
Metals of the 3d series are generally more reactive except …
Cu
Ti, V and Cr are strong …
reducing agents
Which kind of substance id repelled by a magnetic field?
Diamagnetic
Which kind of substance is attracted by a magnetic field?
Paramagnetic
What kind of substance is strongly attracted to a magnetic field?
Ferromagnetic
The energy of excitation corresponds to the…
frequency of the light absorbed
The frequency of light that is absorbed is determined by …?
- Nature of the Ligand
- Size of the ion
- ox.state of the ion
The reasons for complex formation
- small metal ions
- High ionic charges
- Availability of d orbitals
Catalysts are more effective cuz…
- of their varaible oxidation states. e.g. Fe3+ catalyses 2I- + 2S2O8^2-.
- To form complexes
Alloys are formed by metals whoses atomic radii and within………… percentage of one another.
15%
elements involved in
- brass
- bronze
- Cu-Zn
* Cu-Sn
What kind of oxides do d block elements (except Sc form ?
Ionic
As the oxidation no. increases, ………………. increases.
ionic character
Mn2O7 is a green oil and it is ………………..
Covalent
Acidic character is predominant in
higher oxides
From which ore is K2Cr2O7 prepared
Chromite ore (FeCr2O4)
Mn2O7, CrO3, V2O5, CrO, Cr2O3. Classify them as acidic, basic or amphoteric.
- Acidic- Mn2O7, CrO3
- Basic - CrO
- Amphoteric- Cr2O3, V2O5
……………….. solution of Na2Cr2O7 is filtered and mixed with H2SO4 to give a solution from which …………. Na2Cr2O7.2H2O i obtained.
- Yellow
* Orange
Which is more soluble Na2Cr2O7 or K2Cr2O7?
Na2Cr2O7
Laboratory preparation of MnO4- .
2Mn^2+ + 5S2O8^2- + 8H2O = 2MnO4- + 10SO4^2- + 16H+
Why are KMnO4 rxns with HCl unsatisfactory?
because HCl is oxidised to chorine.
Describe the crystals of KMnO4
Dark purple, almost black, which are isostructural with those of KClO.
Magnetism of manganate and permanganate ions respectively are…?
Green Manganate ions are- paramagnetic
Permanganate ions are - diamagnetic
how does pi bonding take place in in KMnO4?
Overlap pf p orbital of oxygen with d orbital of manganese
What transition metal compounds are usually catalysts?
Oxides
What is used as a catalyst for the hydrogenation of oils?
Nickel. (finely divided)
What is the catalyst for the contact process?
Finely divided platinum, V2O5
