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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:
Ionisation enthalpies
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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.
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संबंधित प्रश्न
Give reasons:
Transition metals show variable oxidation states.
|
`E_((M^(2+)/M)` |
Cr | Mn | Fe | Co | Ni | Cu |
| -0.91 | -1.18 | -0.44 | -0.28 | -0.25 | -0.34 |
From the given data of E0 values, answer the following questions :
(1) Why is `E_(((Cu^(2+))/(Cu)))` value exceptionally positive
(2) Why is `E_(((Mn^(2+))/(Mn)))` value is highly negative as compared to other elements
(3) Which is the stronger reducing agents Cr2+ or Fe2+ ? Give Reason.
What may be the stable oxidation state of the transition element with the following d electron configuration in the ground state of its atom?
3d3
NF3 is possible, but NF5 is not. Why?
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.
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 ?
Explain why transition elements form alloys.
Explain why transition metals and their compounds act as a catalyst.
Maximum magnetic moment is shown by ____________.
Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?
(i) \[\ce{Co^{2+}}\]
(ii) \[\ce{Cr^{2+}}\]
(iii) \[\ce{Mn^{2+}}\]
(iv) \[\ce{Cr^{3+}}\]
Which of the following ions show higher spin only magnetic moment value?
(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
A solution of \[\ce{KMnO4}\] on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?
Assertion: \[\ce{Cu^2+}\] iodide is not known.
Reason: \[\ce{Cu^2+}\] oxidises \[\ce{I^-}\] to iodine.
Assertion: Separation of \[\ce{Zr}\] and \[\ce{Hf}\] is difficult.
Reason: Because \[\ce{Zr}\] and \[\ce{Hf}\] lie in the same group of the periodic table.
On adding NaOH, solution to the aqueous solution of K2CrO7 the colour of the solution changes from
Which of the following characteristics of transition metals is associated with their catalytic activity?
What is the oxidation state of chromium in chromate ion and dichromate ion?
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with H2S.
