Q22 of 35 Page 1

The magnetic moments of few transition metal ions are given below:























Metal ion



Magnetic moment(BM)



Sc3+



0.00



Cr2+



4.90



Ni2+



2.84



Ti3+



1.73



(at no. Sc = 21, Ti =22, Cr = 24, Ni = 28)


Which of the given metal ions :


(i) has the maximum number of unpaired electrons?


(ii) forms colourless aqueous solution?


(iii) exhibits the most stable +3 oxidation state?

(i) For scandium (Sc3+)


Theatomic number of Scandium (Sc) is Z = 21.


The electronic configuration of 21Sc= [Ar] 3d1 4s2


And, the electronic configuration of Sc3+= [Ar]3d0, i.e., there are no electrons in 3d subshell.



For chromium (Cr2+)


Theatomic number of chromium (Cr) is Z = 24.


The electronic configuration of 24Cr= [Ar] 3d5 4s1


And, the electronic configuration of Cr2+= [Ar]3d4, i.e., there are 4 unpaired electrons.



For nickel (Ni2+)


Theatomic number of nickel (Ni) is Z = 28.


The electronic configuration of 28Ni= [Ar] 4s2 3d8


And, the electronic configuration of Ni2+= [Ar]3d8, i.e., there are 2 unpaired electrons.



For titanium (Ti3+)


Theatomic number of titanium (Ti) is Z = 22.


The electronic configuration of 22Ti= [Ar] 3d2 4s2


And, the electronic configuration of Ti3+= [Ar]3d1, i.e., there is one unpaired electron.



Thus, Cr3+ having greater no. of unpaired electrons i.e., 4


(ii) As we know that those with fully-filled or empty d-orbitals are colourless. Thus, Sc3+ forms colourless compounds because it has empty d-orbital.


Note: Only those ions will be coloured which have incompletely filled d-orbitals.


(iii) Sc3+ exhibits the most stable +3 oxidation state. Because it has an empty d-orbital. As Ti3+ also exists in +3 oxidation state but is not stable due to the presence of an unpaired electron in the d-orbital.


More from this chapter

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20

Describe the role of

(i) NaCN in the extraction of gold from its ore.


(ii) Cryolite in the extraction of aluminium from pure alumina.


(iii) CO in the purification of Nickel

 21

A metal ion Mn+ having d4 valence electronic configuration combines with three bidentate ligands to form a complex compound. Assuming Δ0 > P:

(i) Write the electronic configuration of d4 ion.


(ii) What type of hybridisation will Mn+ ion has?


(iii) Name the type of isomerism exhibited by this complex.

 22

Consider the standard electrode potential values (M2+ / M) of the elements of the first transition series.


Explain:


(i) Eo value for copper is positive.


(ii) Eo value of Mn is more negative as expected from the trend.


(iii) Cr2+ is a stronger reducing agent than Fe2+

 23

Ashwin observed that his friend Shubham was staying aloof, not playing with friends and becoming easily irritable for some weeks. Ashwin told his teacher about this, who, in turn, called Shubham’s parents and advised them to consult a doctor. Doctor after examining Shubham prescribed antidepressant drugs for him.

After reading the above passage, answer the following questions:


(i) Name two antidepressant drugs.


(ii) Mention the values shown by Ashwin.


(iii) How should Shubham’s family help him other than providing medicine?


(iv) What is the scientific explanation for the feeling of depression?