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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:
Electronic configurations
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उत्तर १
The electronic configurations of the elements of the same group are generally similar.
The first transition series shows two exceptions:
Cr = 3d5 4s1 and Cu = 3d10 4s1
The second series shows more exceptions:
Mo (42) = 4d5 5s1, Tc (43) = 4d6 5s1, Ru (44) = 4d7 5s1, Rh (45) = 4d8 5s1, Pd (46) = 4d10 5s0, Ag (47) = 4d10 5s1
Similarly, the third series shows exceptions:
W (74) = 5d4 6s1, Pt (78) = 5d9 6s1 and Au (79) = 5d10 6s1
Therefore, in many cases in the horizontal series, the electronic configurations of the three series are not the same.
उत्तर २
The first transition series gradually fills 3d-orbitals, whereas the second and third transition series gradually fill 4d-orbitals and 5d-orbitals, respectively.
Notes
Students can refer to the provided solutions based on their preferred marks.
संबंधित प्रश्न
Explain why is Fe3+ more stable than Fe2+?
To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.
What may be the stable oxidation state of the transition element with the following d electron configurations in the ground state of its atom?
3d3
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 stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+.
What are inner transition elements?
Write the factors which are related to the colour of transition metal ions.
Why do transition elements show variable oxidation states ? In 3d series (Sc to Zn), which elements shows the maximum number of oxidation state and why ?
Why do transition metals exhibit higher enthalpy of atomization?
Explain why Mn2+ is more stable than Fe2+ towards oxidation to +3 state. (At. no. of Mn = 25, Fe = 26)
Which of the following will not act as oxidising agents?
(i) \[\ce{CrO3}\]
(ii) \[\ce{MoO3}\]
(iii) \[\ce{WO3}\]
(iv) \[\ce{CrO^{2-}4}\]
Why EΘ values for Mn, Ni and Zn are more negative than expected?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) | Column II (Metal) | |
| (i) | An element which can show +8 oxidation state | (a) \[\ce{Mn}\] |
| (ii) | 3d block element that can show | (b) \[\ce{Cr}\] |
| upto +7 oxidation state | (c) \[\ce{Os}\] | |
| (iii) | 3d block element with highest melting point | (d) \[\ce{Fe}\] |
The standard electrode potentials of four elements A, B, C and D are – 3.05, – 1.66, – 0.40 and + 0.80. The highest chemical reactivity will be exhibited by
Which of the following statements is not correct?
Consider the following standard electrode potential values:
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\], E0 = +0.77 V
\[\ce{MnO^{-4}_{ (aq)} + 8H^+ + 5e^- -> Mn^{2+}_{ (aq)} + 4H2O_{(l)}}\], E0 = +1.51 V
What is the cell potential for the redox reaction?
A transition element X has an electronic configuration [Ar]4s23d3. Predict its likely oxidation states.
The second ionization enthalpies of chromium and manganese are 1592 and 1509 kJ/mol respectively. Explain the lower value of Mn.
Account for the following:
Zirconium (Zr) and Hafnium (Hf) are difficult to separate.
