Advertisements
Advertisements
Question
How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?
Advertisements
Solution
- Ionization enthalpies are found to increase in the given series due to a continuous filling of the inner d-orbitals. The irregular variations of ionization enthalpies can be attributed to the extra stability of configurations such as d0, d5 and d10. Since these states are exceptionally stable, their ionization enthalpies are very high.
- In terms of first ionization energy, Cr has a low ionization energy. This is because after losing one electron, it attains the stable configuration (3d5). On the other hand, Zn has exceptionally high first ionization energy, as an electron has to be removed from stable and fully-filled orbitals (3d10 4s2).
- The second ionization energies are higher than the first since it becomes difficult to remove an electron when an electron has already been removed. Also, elements like Cr and Cu have exceptionally high second ionization energies, as after losing the first electron, they have attained the stable configuration (Cr+: 3d5 and Cu+: 3d10). Hence, removing one more electron from this stable configuration will require a lot of energy.
APPEARS IN
RELATED QUESTIONS
Calculate the ‘spin only’ magnetic moment of \[\ce{M^{2+}_{( aq)}}\] ion (Z = 27).
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
What is meant by ‘disproportionation’?
Complete and balance the following chemical equations
`Fe^(2+) + MnO_4^(-) + H^+ ->`
Give reasons Iron has the higher enthalpy of atomization than that of copper.
Why does the density of transition elements increase from Titanium to Copper? (at. no. Ti = 22, Cu = 29)
Account for the following :
Ti4+ is colourless whereas V4+ is coloured in an aqueous solutions.
Explain why Zn2+ salts are white whereas Cu2+ salts are coloured.
Which is the most stable oxidation state of iron?
The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment.
Which of the following ions show higher spin only magnetic moment value?
(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?
Match the catalysts given in Column I with the processes given in Column II.
| Column I (Catalyst) | Column II (Process) |
| (i) \[\ce{Ni}\] in the presence of hydrogen | (a) Zieglar Natta catalyst |
| (ii) \[\ce{Cu2C12}\] | (b) Contact process |
| (iii) \[\ce{V2O5}\] | (c) Vegetable oil to ghee |
| (iv) Finely divided iron | (d) Sandmeyer reaction |
| (v) \[\ce{TiCl4 + Al (CH3)3}\] | (e) Haber's Process |
| (f) Decomposition of KCIO3 |
Answer the following question:
Which element of the first transition series has highest third ionisation enthalpy?
If enthalpies of formation of C2H4(g), CO2(g) and H2O(l) at 25°C and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, the change in ethalpy for combustion of C2H4 is equal to
Give reasons for the following statement:
Transition metals and most of their compounds show paramagnetic behaviour.
The second ionization enthalpies of chromium and manganese are 1592 and 1509 kJ/mol respectively. Explain the lower value of Mn.
Explain the use of different transition metals as catalysts.
The compounds of \[\ce{Ti^4+}\] ions are colourless due to ______.
Give a reason for the following:
Zinc, cadmium and mercury are considered as d-block elements but not regarded as transition elements.
