Advertisements
Advertisements
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:
Ionisation enthalpies
Advertisements
उत्तर
- In every series, the first ionisation enthalpy generally increases gradually as we move from left to right, although some exceptions are observed in every series.
- In the same respective vertical column (group), the first ionisation enthalpy of some elements of the 4d series is higher, and that of some elements is lower as compared to the elements of the 3d series, although the first ionisation enthalpy of the 5d series is significantly higher as compared to the 3d and 4d series.
- The reason for this is the poor shielding effect of the 4f electrons in the 5d series (known as lanthanoid contraction), which increases the effective nuclear charge and binds the outermost electrons very tightly.
APPEARS IN
संबंधित प्रश्न
How would you account for the following?
Transition metals exhibit variable oxidation states.
Account for the following:
Cu+ ion is unstable in aqueous solution.
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.
Which of the d-block elements may not be regarded as the transition elements?
Compare the stability of +2 oxidation state for the elements of the first transition series.
Use Hund’s rule to derive the electronic configuration of Ce3+ ion and calculate its magnetic moment on the basis of ‘spin-only’ formula.
Give reasons:
E° value for the Mn3+/Mn2+ couple is much more positive than that for Fe3+/Fe2+.
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 ?
Which of the following ions show higher spin only magnetic moment value?
(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
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?
Explain why does colour of KMnO4 disappear when oxalic acid is added to its solution in acidic medium.
Match the catalysts given in Column I with the processes given in Column II.
| Column I (Catalyst) | Column II (Process) |
| (i) \[\ce{Ni}\] in the presence of hydrogen | (a) Zieglar Natta catalyst |
| (ii) \[\ce{Cu2C12}\] | (b) Contact process |
| (iii) \[\ce{V2O5}\] | (c) Vegetable oil to ghee |
| (iv) Finely divided iron | (d) Sandmeyer reaction |
| (v) \[\ce{TiCl4 + Al (CH3)3}\] | (e) Haber's Process |
| (f) Decomposition of KCIO3 |
Mention the type of compounds formed when small atoms like H, C and N get trapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.
Consider the following standard electrode potentials (E° in volts) in aqueous solution:
| Element | M3+/M | M+/M |
| Al | - 1.66 | +0.55 |
| Tl | + 1.26 | -0.34 |
Based on these data, which of the following statements is correct?
In the ground state of atomic Fe (Z = 26), the spin-only magnetic moment is ______ × 10-1 BM.
(Round off to the nearest integer).
[Given: `sqrt3 = 1.73, sqrt2 = 1.41`]
The given graph shows the trends in melting points of transition metals:
Explain the reason why Cr has the highest melting point and manganese (Mn) has a lower melting point.
Account for the following:
Copper has an exceptionally positive `"E"_("M"^(2+)//"M")^0` value.
The trend of which property is represented by the following graph?
