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प्रश्न
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
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उत्तर
As the oxidation state of the element increases, its charge increases. To Fajans rules, as the charge of the metal ion increases covalent character increases because the positively charged cation attracts the electron cloud on the anion towards itself.
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संबंधित प्रश्न
Account for the following:
Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows oxidation state of +4.
Give reasons:
Transition metals show variable oxidation states.
Account for the following:
E° value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+.
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with iodide.
Compare the stability of +2 oxidation state for the elements of the first transition series.
Write the factors which are related to the colour of transition metal ions.
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.
Why does the density of transition elements increase from Titanium to Copper? (at. no. Ti = 22, Cu = 29)
The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.
Transition metals with lowest melting point is ______.
Read the passage given below and answer the following question:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
Assertion: Cations of transition elements occur in various valence states.
Reason: Large number of oxides of transition elements are possible.
Which of the following statements is not correct?
Out of \[\ce{Cu2Cl2}\] and \[\ce{CuCl2}\], which is more stable and why?
Although \[\ce{Cr^3+}\] and \[\ce{Co^2+}\] ions have same number of unpaired electrons but the magnetic moment of \[\ce{Cr^3+}\] is 3.87 B.M. and that of \[\ce{Co^2+}\] is 4.87 B.M. Why?
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.
A violet compound of manganese (A) decomposes on heating to liberate oxygen and compounds (B) and (C) of manganese are formed. Compound (C) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C) with conc. \[\ce{H2SO4}\] and \[\ce{NaCl}\], chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds A to D and also explain the reactions involved.
What is the oxidation state of chromium in chromate ion and dichromate ion?
A pair of coloured ions is ______.
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with iron (II) solution.
