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प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
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उत्तर
The melting points of interstitial compounds are higher than those of pure metals because of bonding between the metal and the non-metal, which is stronger than metal–metal bonding.
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संबंधित प्रश्न
What are interstitial compounds?
Which of the following cations are coloured in aqueous solutions and why ?
Sc3+, V3+, Ti4+, Mn2+ (At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)
Account for the following:
Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows oxidation state of +4.
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Write the element which shows maximum number of oxidation states. Give reason.
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element shows only +3 oxidation state?
In 3d series (Sc to Zn), which element has the lowest enthalpy of atomisation and why?
How would you account for the following : Transition metals form coloured compounds
How would you account for the following:
Of the d4 species, Cr2+ is strongly reducing while manganese (III) is strongly oxidising.
What is meant by ‘disproportionation’?
Use Hund’s rule to derive the electronic configuration of Ce3+ ion and calculate its magnetic moment on the basis of ‘spin-only’ formula.
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
Why do transition metal ions possess a great tendency to form complexes?
Which is the most stable oxidation state of iron?
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.
The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment.
Why is \[\ce{HCl}\] not used to make the medium acidic in oxidation reactions of \[\ce{KMnO4}\] in acidic medium?
Why does copper not replace hydrogen from acids?
Out of \[\ce{Cu2Cl2}\] and \[\ce{CuCl2}\], which is more stable and why?
The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?
Answer the following question:
Which element of the first transition series has highest third ionisation enthalpy?
Identify the metal and justify your answer.
Carbonyl \[\ce{M(CO)5}\]
Which of the following is non-metallic?
The orientation of an atomic orbital is governed by
The product of oxidation of I– with \[\ce{MnO^{-}4}\] in alkaline medium is:-
How is the variability in oxidation states of transition metals different from that of p-block elements?
Which of the following ions acts as a typical transition metal ion?
Account for the following:
Eu2+ with electronic configuration [Xe]4f76s2 is a strong reducing agent.
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
