Long Answer Type(a) Comment on the following tendencies of transition elements of first series:
(i) They exhibit variable oxidation states.
(ii) They easily form alloys.
(iii) They often act as catalyst.
(b) State the different characteristic of actinoids and lanthanoids which places them in f-block elements.
(c) How many unpaired electrons are there in Ni2+(aq)?
Account for the following:
(a) Transition elements have high boiling point and high enthalpy of atomisation.
(b) Zn, Cd, Hg are normally not regarded as transition elements.
(c) Transition metals generally form alloys with other transition metals.
(d) Transition metals form a number of interstitial compounds.
(e) Ni2+ compounds are thermodynamically more stable than Pt2+ compounds.
(i) What are inner transition elements? Write their general electronic configuration.
(ii) The chemistry of the actinoid elements is not so smooth as that of the Lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements?
Describe the general characteristics of the transition elements with special reference to their tendency to
(i) exhibit paramagnetism, (ii) form complex compounds, (iii) their catalytic behaviour.
i) Paramagnetism is due to presence of one or more unpaired electrons which are attracted by the magnetic. The electronic configuration of transition element is (n-1)d1–10ns1–2. Thus in transition element number of unpaired electron exist. Paramagnetic materials include magnesium, molybdenum, lithium, and tantalum
also always transition metals have unpaired d-electron.
ii) The transition metals form a large number of complex compounds. This is due to the comparatively smaller sizes of the metal ions, their high ionic charges and the availability of d orbitals for bond formation. A few examples are: [Fe(CN)6]3–, [Fe(CN)6]4–,[Cu(NH3)4]2+ and [PtCl4]2–.
iii) The most important reason transition metals are good catalysts is that they can lend electrons or withdraw electrons from the reagent, depending on the nature of the reaction. The ability of transition metals to be in a variety of oxidation states, the ability to interchange between the oxidation states and the ability to form complexes with the reagents and be a good source for electrons make transition metals good catalysts.
Short Answer TypeWhat are the transition elements? Write two characteristics of the transition elements ?
How would you account for the following?
Actinoid contraction is greater than lanthanoid contraction.
Which metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
Which of the following cations are coloured in aqueous solutions and why?
Sc3+, V3+, Ti4+, Mn2+ (Atomic number Sc = 21, V = 23, Ti = 22, Mn = 25)
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