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प्रश्न
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:
Ionisation enthalpies
उत्तर
In every series, the first ionization enthalpy generally increases gradually as we move from left to right, although some exceptions are observed in every series. In the same horizontal group, the first ionization enthalpy of some elements of 4d series is higher and that of some elements is lower as compared to the elements of 3d series, although the first ionization enthalpy of 5d series is higher as compared to 3d and 4d series. The reason for this is the weak shielding effect of the nucleus on the 4f electrons in the 5d series.
संबंधित प्रश्न
What are the transition elements? Write two characteristics of the transition elements.
Complete and balance the following chemical equations
`Fe^(2+) + MnO_4^(-) + H^+ ->`
Account for the following :
Ti4+ is colourless whereas V4+ is coloured in an aqueous solutions.
Transition metals with lowest melting point is:
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 halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
A metallic ion 'M' reacts with chloride ion to form white precipitate which is readily soluble in aqueous ammonia. Identify 'M'?
Match List - I with List - II.
| List - I | List - II | ||
| (a) | \[\ce{[Fe(CN)6]^3-}\] | (i) | 5.92 BM |
| (b) | \[\ce{[Fe(H2O)6]^3+}\] | (ii) | 0 BM |
| (c) | \[\ce{[Fe(CN)6]^4-}\] | (iii) | 4.90 BM |
| (d) | \[\ce{[Fe(H2O)6]^2+}\] | (iv) | 1.73 BM |
Choose the correct answer from the options given below.
The second ionization enthalpies of chromium and manganese are 1592 and 1509 kJ/mol respectively. Explain the lower value of Mn.
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with H2S.
