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प्रश्न
Transition elements show high melting points. Why?
Explain giving reasons:
Transition elements have higher melting and boiling points.
Why do transition elements have much higher melting points?
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उत्तर १
The high melting points of transition metals are attributed to the involvement of greater number of electrons in the interatomic metallic bonding from (n – 1) d-orbitals in addition to ns electrons.
उत्तर २
- Transition elements have higher melting and boiling points because their atoms are held together by strong metallic bonds.
- These metallic bonds have significant covalent character due to the presence of unpaired d-electrons that overlap between atoms.
- More unpaired d-electrons mean more covalent bonding and stronger metallic bonds, which require more energy to break.
- The close-packed structures of transition metals also contribute to the strong bonding and thus high melting and boiling points.
- Melting and boiling points generally increase up to the middle of the series because the number of unpaired d-electrons also increases up to that point.
संबंधित प्रश्न
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Electronic configurations
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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.
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