Answer: (ii) 5f orbitals have poor shielding effect than 4f orbitals, therefore, effective nuclear charge is more in actinoids than lanthanoids. Find 1 Answer & Solution for the question Why do actinoids show a wide range of oxidation states ? (ii) Mn3+ gains one electron to form Mn2+ since 3dD is more stable, whereas Cr2+ loses one electron for Cr3+(i3p which is more stable, so, it acts as reducing agent. Ytterbium (Yb) also shows +2 oxidation state. Answer: ‘ to Q.30 (iii). Electrons do not flow around by themselves but they must be provided by some sources . Misch metal is used in Mg-based alloy to produce bullets, shell and lighter flint. (a) How do you prepare: Why? (i) Transition metals generally form coloured compounds. Question 43: (b) Zinc does not have unpaired electrons and larger in size, therefore, it has weak metallic bonds. to Q.35 (i). Explain giving reasons: (ii) The higher oxidation states are usually exhibited by the members in the middle of a series of transition elements. Actually, i believe its not JUST actinoids, but basically all elements that are period 5 and lower. (ii) Refer Ans. The higher ionisation energies of the actinides tend to be smaller than those of the lanthanides, for the same reasons as explained in the linked question (5f orbitals have one radial node; 4f orbitals do not). Answer: (ii) In a transition series of metals, the metal which exhibits the greatest number of oxidation states occurs in the middle of the series. Question 62: Question 2: (i) Zn is not considered as a transition element. By that those ions become strong reducing or oxidizing agents respectively. In 3d series (Sc to Zn), which element shows the maximum number of oxidation states and why? (a) Why do transition elements show variable oxidation states? to Q.41 (ii). (ii) Lanthanoids show limited number of oxidation state, viz. (iii) The members in the actinoid series exhibit a larger number of oxidation states than the corresponding members in the lanthanoid series. Consequences: (i) Potassium dichromate from sodium chromate and (ii) E°CU9+/CU has +ve value due to high ionisation enthalpies and sublimation energies and lower hydration energy. (ii) It is because transition metals in lowest oxidation state are more metallic and in higher oxidation state are least metallic, therefore, oxides in lower oxidation state are basic, whereas in higher oxidation state are amphoteric/acidic. (a) (i) It is because hydration energy of Cu2+ overcomes 2nd ionisation enthalpy, that is why Cu+ changes to Cu2+ and Cu. (iv) Out of Mn3+ and Cr3+, which is more paramagnetic and why? Answer: (b) What is lanthanoid contraction? (ii) Metal-metal bonding is more frequent for the 4d and the 5d series of transition metals than that for the 3d series. Answer: This is because Option 1) the orbitals extend further from the nucleus than the orbitals Option 2) the orbitals are more buried than the orbitals Option 3) there is a similarity between and orbitals in their angular part of the wave function Option 4) the actinoids are more reactive than the lanthanoids. • (i) It is because they show variable oxidation states and have vacant rf-orbitals The known oxidation states of actinoids are listed in Table 8.11. Account for the following: (ii) Mns+(3d4) is strongly oxidising, whereas Cr2+(3d4) is strongly reducing. Lower the oxidation state, more will be basic nature, e.g. to Q.41 (ii). Answer: (ii) They form coloured compounds. (b) (i) Refer Ans. Answer: (i) Mn because it has five unpaired electrons and 2 electrons in s-orbital which can take part in bond formation, therefore, it shows maximum number of oxidation states. (a) What are the different oxidation states exhibited by the lanthanoids? to Q.47 (i) (ii) Refer Ans. Question 25: Write one similarity between the chemistry of lanthanoids and actinoids… For example, uranium, neptunium and plutonium form salts of the Na 2 UO 4 (uranate) and (NH 4) 2 U 2 O 7 (diuranate) types. Similarity: Question 22: None of the oxygen-containing compounds are peroxides or superoxides. - or - email: password: Log in Forgot password? (i) It is because 5f, 6d and 7s have comparable energy. * Actinides show a variety of oxidation states from +3 to +6. to Q.29 (i). The word valence is used inconsistently to mean either one or the other. (a) Complete the following chemical reaction equations: Answer: Answer: (i) It is because 5f, 6d and 7s have comparable energy. (a) Copper exhibits +1 oxidation state frequently due to stable electronic configuration. (i) Small size atoms, such as B, C and H can occupy voids present in transition metals. (i) Name the element showing maximum number of oxidation states among the first series of transition metals from Sc (Z = 21) to Zn (Z = 30). (i) It is due to presence of five unpaired electrons. None of the oxygen-containing compounds are peroxides or superoxides. (ii) Cr2O7-(aq) + H2S(g) + H+(ag) ——–> Lanthanide oxidation states All of the lanthanide elements are commonly known to have the +3 oxidation state and it was thought that only samarium, europium, and ytterbium had the +2 oxidation readily accessible in solution. Answer: Actinoid contraction. (iii) It is due to absence of unpaired electrons, they do not absorb light from visible region and do not radiate colour. Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. (iii) Mn3+ is stronger oxidising agent because it can gain electrons to become Mn2+ which is more stable due to 3d5 (half filled d-orbitals), whereas Cr3+ is stable due to f3 (half filled orbitals). It is attained by removing outermost 2 electrons of 6s electrons and 1 electron from 4f electrons. (a) (i) Refer Ans. (i) Cr2+ is reducing in nature while with the same d-orbital configuration (d4) Mn3+ is an oxidising agent. The oxidation state of a free element (uncombined element) is zero. (ii) The metallic radii of the third (5d) series of transition elements are virtually the same as those of the corresponding members of the second series. (b) It contains 95% lanthanoid metal, 5% iron and traces of S, C, Ca and AI. The +4 oxidation state is the most stable in … (iii) Complete the following equation: It is because Cu+2. (ii) Cr202– + H2S + H+ ———-> Eu shows +2, whereas Ce shows +4 oxidation state. Question 9: Write two characteristics of the transition elements. (b) Misch metal is an alloy which contains some of the lanthanoid metals. (iii) Complete the following equation: (i) The transition elements have great tendency for complex formation, The actinoids (5f-element) exhibit more number of oxidation states in general than the lanthanoids because 5f orbitals extend farther from the nucleus than the 4f-orbitals. (i) Why do actinoids show wide range of oxidation states? Answer: (a) A blackish brown solid ‘A’ when forced with alkali metal hydroxide in presence of air, produces a dark green coloured compound ‘B’, which on electrolytic oxidation in alkaline medium gives a dark purple coloured compound ‘C’. (b) Complete the following equations: (iv) The silver atom has completely filled d-orbitals (4d 10 ) in its ground state, yet it is regarded as a transition element. Actinoids also show stable +3 oxidation state but show a number of oxidation states i.e. 3MnO4– + 4H+ ———> (a) Complete the following chemical equations: Question 38: Question 19: (b) What are the common oxidation states of Cerium (At.no. Answer: Some of them can be cut with a knife. Assign reasons for the following :
(i) Copper (I) ion is not known in aqueous solution. (ii) It is due to lanthanoid contraction. Answered By . (b) In the 3d series from Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomization of Zn is the lowest. (iii)Transition metals show variable oxidation states. (i) With the same d-orbital configuration (d4), Cr2+ is a reducing agent while Mn3+ is an oxidising agent. This helps determine the oxidation state of any one element in a given molecule or ion, assuming that we know the common oxidation states of all of the other elements. (i) Transition elements and their compounds are known to act as catalysts. Question 8: 7 s = 7 + 1 = 8. Answer: (i) Copper (I) ion is not known in aqueous solution. Question 28: The prominent oxidation state among actinides is +3. (i) Mn04– (aq) + C2042- (aq) + H+ (aq) ——-> Why do actinoids show a wide range of oxidation states? (i) Name the element of 3d transition series which shows maximum number of oxidation states. (iii) Transition metals have high melting points. (ii) Refer Ans. Though 3+ is the most stable oxidation state, other oxidation states are possible because of the good shielding of f-electrons. (ii) 5f orbitals have poor shielding effect than 4f orbitals, therefore, effective nuclear charge is more in actinoids than lanthanoids. (a) What is meant by the term lanthanoid contraction? Question 64: (i) It is because of strong metallic bonds due to large number of unpaired electrons in d-orbitals. Why? How would you account for the following? Use: Its magnesium based alloy is used to produce bullets, shells, flints. Oxidation occurs when an atom, molecule, or ion loses one or more electrons in a chemical reaction. to Q.30 (i). (b) Explain the following observations: Therefore, its salts are white. The principal oxidation states are +3 and +4 and +3 oxidation state is the most stable. The I.E. (ii) Manganese exhibits the highest oxidation state of+7 among the 3d series of transition elements (b) (i) Refer Ans. Write one similarity and one difference between the chemistry of lanthanoids and that of actinoids. (iii) There is hardly any increase in atomic size with increasing atomic numbers in a series of transition metals. How would you account for the following? Stability of oxidation states. Answer: Tetravalent americium forms stable solid compounds (dioxide, fluoride and hydroxide) as well as complexes in aqueous solutions. (iii) Refer Ans. Write its one use. Question 7: (ii) It is because they show variable oxidation states and have vacant d-orbitals forming unstable intermediates which readily change into products. to Q.40 (iii). to Q.23 (b). Post author: Post published: December 2, 2020 Post category: Uncategorized Post comments: 0 Comments 0 Comments (b) Account for the following: The most common oxides are of the form M 2 O 3, where M would be one of the elements in the Actinide series. (i) Many of the transition elements and their compounds can act as good catalysis. Question 36. (ii) It is because energy required to remove electron is more due to greater effective nuclear charge which is due to lanthanoid contraction. The most common oxidation state; The most stable oxidation state for all trans-Americium elements (except No? to Q.38 (i). But the most stable oxidation state of Lanthanides is +3. 8. The most important isotope is 239 Pu because it is fissionable and has a half-life of 24,100 years, which makes it easy for chemists to study. (ii) It is due to maximum number of unpaired electrons(s). (i) Mn2+ is more stable than Fe2+ towards oxidation to +3 state. Remember, transition metals have varying oxidation states. (ii) Refer Ans. 11. (iii) Actinoid elements show wide range of oxidation states. (iii) Lanthanum and Lutetium do not show colouration in solutions. (iii) 2MnO4+ 4KOH + 02 ———> 2K2Mn04+ 2H20, Question 11: (a) Which metal in the first transition series (3d series) exhibits +1 oxidation state most frequently and why? Obviously, reaction (4.4.17) right is the reverse of reaction (4.4.11).From laboratory investigations and studies of plant data, it has been noticed that reaction (4.4.17) does not reach the equilibrium. Shows the maximum oxidation state compensated by hydration energy soft, have a silvery color ( tarnish... Exhibit + 2 oxidation state of -1 ( i.e metal-metal bonds Verma Pradeep Errorless = 29.. Cr 2 + / Mn ) 0 value highly negative as compared to.. Themselves or their ions have incompletely filled d-orbital question 73: answer: ( )... Captcha proves you are a couple main factors to take into account unstable intermediates which readily change into.. 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