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प्रश्न
Write the factors which are related to the colour of transition metal ions.
Write the conditions of colour of transition metal ions.
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उत्तर
- Metal ions exhibit the presence of incompletely filled d-orbitals.
- The presence of unpaired electrons in d-orbitals.
- The d-d transition of electrons due to absorption of radiation in the visible region.
- The metal ion in the complex undergoes a type of hybridisation.
- The geometry of the complex containing transition metal ions is described.
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संबंधित प्रश्न
How would you account for the following?
Transition metals exhibit variable oxidation states.
How would you account for the following : Transition metals form coloured compounds
Account for the following:
Cu+ ion is unstable in aqueous solution.
How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?
Which of the d-block elements may not be regarded as the transition elements?
How would you account for the following:
Cobalt (II) is stable in aqueous solutions, but in the presence of complexing reagents, it is easily oxidised.
Why do transition metal ions possess a great tendency to form complexes?
The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.
Electronic configuration of Mn2+ 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: Transition metals form protective oxide films.
Reason: Oxides of transition metals are always stoichiometric.
Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d5. What is its atomic number?
Why does copper not replace hydrogen from acids?
Why first ionisation enthalpy of Cr is lower than that of Zn?
Although fluorine is more electronegative than oxygen, but the ability of oxygen to stabilise higher oxidation states exceeds that of fluorine. Why?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
Transition metals can act as catalysts because these can change their oxidation state. How does \[\ce{Fe(III)}\] catalyse the reaction between iodide and persulphate ions?
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:
(activation energy, Threshold energy, increased, lowered, partially, full, d-d transition, Benzoic acid, benzaldehyde)
Only those transition metal ions will be coloured which have ______ filled d-orbitals facilitating ______.
Catalytic hydrogenation of benzene gives
Which of the following statements is not correct?
Sodium this sulphate is used in photography because of its:-
Give reason for the following statement:
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless.
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?
Which one among the following metals of the 3d series has the lowest melting point?
Give two similarities in the properties of Sc and Zn.
What is the oxidation state of chromium in chromate ion and dichromate ion?
Write the ionic equation for reaction of KI with acidified KMnO4.
The compounds of \[\ce{Ti^4+}\] ions are colourless due to ______.
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with iron (II) solution.
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
