Advertisements
Advertisements
Question
Predict which of the following will be coloured in the aqueous solution?
Ti3+, V3+, Cu+, Sc3+, Mn2+, Fe3+ and Co2+. Give reasons for each.
Advertisements
Solution
Only the ions that have electrons in the d-orbital and for which the d-d transition is possible will be coloured. The ions in which d-orbitals are empty or completely filled will be colourless as no d-d transition is possible in those configurations.
| Element | Atomic Number | Ionic State | Electronic configuration in ionic state |
| Ti | 22 | Ti3+ | [Ar] 3d1 |
| V | 23 | V3+ | [Ar] 3d2 |
| Cu | 29 | Cu+ | [Ar] 3d10 |
| Sc | 21 | Sc3+ | [Ar] |
| Mn | 25 | Mn2+ | [Ar] 3d5 |
| Fe | 26 | Fe3+ | [Ar] 3d5 |
| Co | 27 | Co2+ | [Ar] 3d7 |
From the above table, it can be easily observed that only Sc3+ has an empty d-orbital and Cu+ has completely filled d-orbitals. All other ions, except Sc3+ and Cu+, will be coloured in aqueous solution because of d-d transitions.
RELATED QUESTIONS
What are interstitial compounds?
Give reasons:
Transition metals show variable oxidation states.
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
An analysis shows that FeO has a non-stoichiometric composition with formula Fe0.95O. Give reason.
Dissociation of H2S is suppressed in acidic medium.
Why do transition elements show variable oxidation states ? In 3d series (Sc to Zn), which elements shows the maximum number of oxidation state and why ?
Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid-state?
The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment.
Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?
(i) \[\ce{Co^{2+}}\]
(ii) \[\ce{Cr^{2+}}\]
(iii) \[\ce{Mn^{2+}}\]
(iv) \[\ce{Cr^{3+}}\]
Reactivity of transition elements decreases almost regularly from Sc to Cu. Explain.
Which of the following is non-metallic?
The orientation of an atomic orbital is governed by
Catalytic hydrogenation of benzene gives
Which of the following statements is not correct?
Why are all copper halides known except that copper iodide?
Which of the following ions acts as a typical transition metal ion?
Which of the following transition metals shows +1 and +2 oxidation states?
Give a reason for the following:
Zinc, cadmium and mercury are considered as d-block elements but not regarded as transition elements.
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:
Oxidation states
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
