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प्रश्न
Account for the following:
Transition metals form alloys.
Explain why do transition metals form alloys among themselves.
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उत्तर १
Transition metals have very similar atomic sizes as a result one metal can easily replace the other metal from its lattice to form solid solution (alloy). Transition metals are also miscible with one another in the molten state. Thus, the molten state solution of two or more transition metals on cooling forms an alloy.
उत्तर २
- Transition metals have very similar atomic sizes.
- Because of this similarity, one metal atom can easily replace another in the metal lattice.
- This forms a solid solution called an alloy.
- Transition metals are also miscible in their molten state, meaning they mix well when melted.
- Upon cooling, the molten mixture solidifies as an alloy.
- These alloys are usually hard and have high melting points.
Thus, the similar atomic size and good miscibility in the molten state lead transition metals to form alloys easily.
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संबंधित प्रश्न
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`Fe^(2+) + MnO_4^(-) + H^+ ->`
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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.
Match the solutions given in Column I and the colours given in Column II.
| Column I (Aqueous solution of salt) |
Column II (Colour) |
| (i) \[\ce{FeSO2.7H2O}\] | (a) Green |
| (ii) \[\ce{NiCl2.4H2O}\] | (b) Light pink |
| (iii) \[\ce{MnCl2.4H2O}\] | (c) Blue |
| (iv) \[\ce{CoC12,6H2O}\] | (d) Pale green |
| (v) \[\ce{Cu2 Cl2}\] | (e) Pink |
| (f) Colourless |
Which of the following ions will exhibit colour in aqueous solution?
The oxidation state of Fe in [Fe(CO)5] is ______.
