Advertisements
Advertisements
प्रश्न
What are the characteristics of the transition elements and why are they called transition elements?
Advertisements
उत्तर
- Electronic configuration: General electronic configuration is (n − 1) d1−10ns0−2. This configuration reflects the filling of d-orbitals in addition to the s-orbitals of the outermost shell.
- Metallic character: Transition elements, except for Zn, Cd and Hg, exhibit metallic structures and typical metallic properties like malleability, ductility and conductivity.
- Atomic and ionic size: Across a transition series, the atomic and ionic radii decrease due to the increasing nuclear charge, which pulls the d-electrons closer to the nucleus (a phenomenon called the lanthanide contraction).
- Oxidation state: They exhibit variable oxidation states due to the participation of both d and s-electrons in bonding. Common oxidation states range from +2 to +7, depending on the element.
- Paramagnetism: Ions with unpaired d-electrons exhibit paramagnetism. The greater the number of unpaired electrons, the stronger the paramagnetic behaviour.
- Ionisation enthalpy: Ionisation enthalpy increases gradually across the series as the nuclear charge increases, making it harder to remove electrons.
- Formation of coloured ions: Transition metal ions are often colored because of electronic transitions within the d-orbitals (specifically d-d transitions) when they absorb visible light.
- Formation of complex compounds: Transition metals form complexes due to their small size, high charge density, and availability of vacant d-orbitals to accept electron pairs from ligands.
- They possess catalytic properties: They act as catalysts because they can exist in multiple oxidation states, which facilitates various chemical reactions.
- Formation of interstitial compounds: Transition metals can form interstitial compounds by trapping small non-metal atoms (such as H, C, or N) within their crystal lattice.
- Alloy formation: They readily form alloys due to similar atomic sizes, which allows different metal atoms to substitute for one another in the crystal structure.
They are positioned between s and p-block elements and are known as transition elements because of their incompletely filled d-orbitals in the ground state or any stable oxidation state.
संबंधित प्रश्न
What are interstitial compounds?
|
`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.
Write balanced chemical equations for the conversion of `CrO_4^(2-)` to `Cr_2O_7^(2-)` in acidic medium and `Cr_2O_7^(2-)` to `CrO_4^(2-)`
in basic medium.
Which of the following statements is not correct?
Which of the following ions show higher spin only magnetic moment value?
(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
Identify the metal and justify your answer.
\[\ce{MO3F}\]
Which of the following statements is not correct?
Passing H2S gas into a mixture of Mn2+ and Ni2+, Cu2+, ions in an acidified aqueous solution precipitates.
Which of the following ions will exhibit colour in aqueous solution?
Why are all copper halides known except that copper iodide?
Why is the `"E"_(("V"^(3+)//"V"^(2+)))^"o"` value for vanadium comparatively low?
The number of terminal oxygen atoms present in the product B obtained from the following reactions is:
\[\ce{FeCr2O4 + Na2CO3 + O2 -> A + Fe2O3 + CO2}\]
\[\ce{A + H^+ -> B + H2O + Na^+}\]
The value of Δ0 for \[\ce{RhCl^{3-}6}\] is 243 KJ/mol which wavelength of light will promote an electron from. The colour of the complex is ______.
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 trend of which property is represented by the following graph?
In order to protect iron from corrosion, which one will you prefer as a sacrificial electrode, Ni or Zn? Why? (Given standard electrode potentials of Ni, Fe and Zn are -0.25 V, -0.44 V and -0.76 V respectively.)
Give a reason for the following:
Zinc, cadmium and mercury are considered as d-block elements but not regarded as transition elements.
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
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
