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प्रश्न
The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?
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उत्तर
Due to lanthanide contraction, the atomic radii of the second and third row transition elements are almost same. So, they resemble each other much more as compared to first row elements.
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संबंधित प्रश्न
Why is Sc3+ colourless while Ti3+ coloured? (Atomic number Sc = 21, Ti =22)
Why do interstitial compounds have higher melting points than corresponding pure metals?
Account for the following:
Cr2+ is a strong reducing agent.
Account for the following:
Zn is not considered as a transition element.
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:
Electronic configurations
Write the formula of an oxo-anion of Chromium (Cr) in which it shows the oxidation state equal to its group number
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
In lake test for Al3+ ions, there is the formation of coloured ‘floating lake’. It is due to ______.
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: Crystal structure of oxides of transition metals often show defects.
Reason: Ligand field effect cause distortions in crystal structures.
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.
Assertion (A): Cu cannot liberate hydrogen from acids.
Reason (R): Because it has positive electrode potential.
The element with atomic number 46 belongs to
The complex showing a spin-span magnetic moment of 2.82 B.M. is :-
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The basic character of transition metals monoxide follow the order.
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(Round off to the nearest integer).
[Given: `sqrt3 = 1.73, sqrt2 = 1.41`]
Account for the following:
Sc3+ is colourless whereas Ti3+ is coloured in an aqueous solution.
A transition element X has an electronic configuration [Ar]4s23d3. Predict its likely oxidation states.
The trend of which property is represented by the following graph?
