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प्रश्न
Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following point:
Atomic sizes
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उत्तर
- Generally, ions or atoms of the same charge in a series show a gradual decrease in radius with increasing atomic number, although this decrease is very small.
- In the same respective vertical column (group), the size of the atoms of the 4d series is larger than that of the corresponding elements of the 3d series. However, the size of the corresponding elements of the 5d series is almost the same as that of the 4d series.
- The reason for this nearly identical size between 4d and 5d series elements is Lanthanoid Contraction, which cancels out the expected increase in size due to the addition of a new shell.
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संबंधित प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
ln which pair highest oxidation states of transition metals are found:
Calculate magnetic moment of `Fe_((aq))^(2+) ion (Z=26).`
Account for the following:
Cu+2 salts are coloured, while Zn2+ salts are white.
Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their +3 state?
Write down the number of 3d electrons in the following ion:
Cu2+
Indicate how would you expect the five 3d orbitals to be occupied for this hydrated ion (octahedral).
How would you account for the following?
Transition metals and their compounds act as catalysts.
Give reasons Iron has the higher enthalpy of atomization than that of copper.
The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment.
\[\ce{KMnO4}\] acts as an oxidising agent in acidic medium. The number of moles of \[\ce{KMnO4}\] that will be needed to react with one mole of sulphide ions in acidic solution is ______.
Match the solutions given in Column I and the colours given in Column II.
| Column I (Aqueous solution of salt) |
Column II (Colour) |
| (i) \[\ce{FeSO2.7H2O}\] | (a) Green |
| (ii) \[\ce{NiCl2.4H2O}\] | (b) Light pink |
| (iii) \[\ce{MnCl2.4H2O}\] | (c) Blue |
| (iv) \[\ce{CoC12,6H2O}\] | (d) Pale green |
| (v) \[\ce{Cu2 Cl2}\] | (e) Pink |
| (f) Colourless |
Assertion (A): Cu cannot liberate hydrogen from acids.
Reason (R): Because it has positive electrode potential.
If enthalpies of formation of C2H4(g), CO2(g) and H2O(l) at 25°C and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, the change in ethalpy for combustion of C2H4 is equal to
The basic character of transition metals monoxide follow the order.
Why are all copper halides known except that copper iodide?
Give reason for the following statement:
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless.
Why Zn, Cd and Hg are not called transition metals?
A transition element X has an electronic configuration [Ar]4s23d3. Predict its likely oxidation states.
Give a reason for the following:
Transition metals possess a great tendency to form complex compounds.
For M2+/M and M3+/M2+systems, the EΘ values for some metals are as follows:
| Cr2+/Cr | −0.9 V |
| Mn2+/Mn | −1.2 V |
| Fe2+/Fe | −0.4 V |
| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
Use this data to comment upon:
The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
