(ii) Actinoids exhibit greater range of oxidation states than lanthanoids. Question 24: Question 33: Others are colourless due to the absence of unpaired electrons and cannot undergo d-d transitions. (i) Mn04– + C2072- + H+ ——-> (i) Thf enthalpies of atomisation of the transition metals are high. Actinides form basic oxides and hydroxides. 5 (ii). which one of these in the most stable in aqueous solutions? Answer: (i) E° value for the Mn+3/Mn+2 couple is positive (+1.5 V) whereas that of Cr+3/Cr+2 is negative (-0.4 V). (ii) Why is actinoid contraction greater than lanthanoid contraction? Answer: (ii) Actinoids exhibit greater range of oxidation states than lanthanoids. View Answer. It is due to similar energy of (n – 1 )d and ns orbitals, electrons from both can be lost. Though 3+ is the most stable oxidation state, other oxidation states are possible because of the good shielding of f-electrons. Mention its two uses. Actinides are typical metals. It is because neither Zn nor Zn+2. (ii) Transition metals form complex compounds Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. Now, it is known that all of the lanthanides can form +2 complexes in solution. The wide range of oxidation states of actinoids is attributed to the fact that the 5f, 6d and 7s energy levels are of comparable energies. There is a greater range of oxidation states, which is in part attributed to the fact that the 5f, 6d and 7s levels are of comparable energies. Actinides show variable oxidation states because of the smaller energy gap between 5f, 6 d and 7s orbitals. (iii) Refer Ans. They have the ability to form complexes with ligands such as chlorides, sulfates, etc. (iii) Most of the transition metal ions exhibit characteristic colours in aqueous solutions (i) It is because of strong metallic bonds due to large number of unpaired electrons in d-orbitals. (iii) It is because 5f, 6d and 7s have comparable energy. to Q.9 (ii). (ii) Metal-metal bonding is more frequent for the 4d and the 5d series of transition metals than that for the 3d series. The decrease in size with the increase in atomic number among lanthanoids is called lanthanoid contraction. (ii) Refer Ans. to Q.9 (i). (ii) Actinoids exhibit a much larger number of oxidation states than the lanthanoids. For any content/service related issues please contact on this number . (ii) Transition metals form alloys. to Q.36 (ii). (iii) Zn has lowest enthalpy of atomisation. (i) The gradual decrease in size (actinoid contraction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction). (ii) It is because neither Zn nor Zn2+ ions have incompletely filled d-orbitals. Answer: Manganese has a very wide range of oxidation states in its compounds. Explain the following observations: (i) They show variable oxidation state. to Q.35 (i). Why? Answer: Question 55: Answer: (i) Fe2+ ions (i) Transition elements and their compounds are known to act as catalysts. Iron has two common oxidation states (+2 and +3) in, for example, Fe 2+ and Fe 3+. (ii) Mn(III) undergoes disproportionation reaction easily. Write the ionic equations for the reactions involved. When present in most compounds, hydrogen has an oxidation state of +1 and oxygen an oxidation state of −2. (ii) Mn has electronic configuration (Ar) 4s2 3d5 and all the electrons in ‘s’ as well as ‘d’ orbitals can take part in bond formation, therefore, it shows + 7 highest oxidation state. to Q.23 (b). to Q.30 (i). Some just lose one electron to form +3 … (ii) There occurs much more frequent metal-metal bonding in compounds of heavy transition metals (i.e. (ii) It is due to lanthanoid contraction. Create free account. (ii) It is due to presence of unpaired electrons which participate in metal-metal bonding in 5d series (3rd series). (iii) Refer Ans. The reason for greater range of oxidation states in actinoids is attributed to. Lanthanoids show limited oxidation states(+2,+3,+4). Question 45: (i) Refer Ans. • Their separation becomes difficult. Find 1 Answer & Solution for the question Why do actinoids show a wide range of oxidation states ? . Although the lanthanides are sometimes called the rare earths, the elements are not particularly rare. * Actinides show a variety of oxidation states from +3 to +6. (b) Name an important alloy which contains some of the lanthanoid metals. 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. (b) What is lanthanoid contraction? (iii) The E° value for the Mn3+/Mn2 + couple is much more positive than that for Cr3+/Cr2+ couple. (iii) Refer Ans. (ii) Which transition metal of 3d series has positive E°(M2+/M) value and why? How would you account for the following: It is useful to have a way of distinguishing between the charge on a transition-metal ion and the oxidation state of … Why? (ii) Cr2072 – + 14H+ + 6Fe2+ ———> 2Cr3+ + 7H20 + 6Fe3+. Write two characteristics of the transition elements. (ii) The actinoids exhibit a large number of oxidation states than the corresponding members in the lanthanoid series. In 3d series (Sc to Zn), which element shows the maximum number of oxidation states and why? (a) What are the different oxidation states exhibited by the lanthanoids? (b) Explain the following observations: 6 d = 6 + 2 = 8. Transition elements show variable oxidation states because electrons from both s and d orbitals take part in bond formation. (iii) The members in the actinoid series exhibit larger number of oxidation states than the corresponding members in the lanthanoid series. Give reasons : Answer: (i) Metal-metal bonding is more extensive in the 4d and 5d series of transition elements than the 3d series. In d-block, oxidation states differ by one, whereas in p-block, it differs by two. Question 49: (i) Refer Ans. Question 5: (a) (i) Refer Ans. Higher the oxidation state, more will be acidic nature, e.g. The E 0 ( M 2+ / M ) value of a metal depends on the energy changes involved in the formation of the M 2+ ion: Why do transition elements show variable oxidation states? (c) Why do actinoids show a wide range of osidation states? to Q.16 (a) (ii). to Q.41 (ii). Answer: (i) Refer Ans. 16 (a) (ii). To reach a higher oxidation state, one obviously has to pay for it in the form of ionisation energy/energies. (i) It is because of presence of unpaired electrons in d-orbitals of transition metal. to Q.5 (ii). Question 37: Question 50: (ii) It is due to presence of unpaired electrons which undergo d-d transition by absorbing light from visible region and radiate complementary colour. (iii) Refer Ans. +2, +3 and +4 (out of which +3 is most common) because of large energy gap between 4f and 5d subshells. Answer: So, which do you mean? (a) Complete the following reactions in an aqueous medium: Answer: 46. Explain the following observations giving an appropriate reason for each: (i) It is due to lanthanoid contraction which is due to poor shielding effect of f-electrons. However, there is a compensatory effect in that elements in higher oxidation states generally get more out of bonding. (b) Account for the following: Answer: Answer: Question 14: On the other hand Actinoids show a large number of oxidation states because of small energy gap between 5f, 6d and 7s subshell. • The lanthanoids have similar ionic size and resemble with each other closely in their properties. Why Lanthanide show Variable Oxidation State? (iv) Out of Mn3+ and Cr3+, which is more paramagnetic and why? (i) Zn is not considered as a transition element. Assign reasons for the following: Question 71: Sc3+, V3+, Ti4+, Mn2+ Please enable Cookies and reload the page. (ii) Cr2O7-(aq) + Fe2+ (aq) + H+(aq) ——-> Manganese: Manganese has a very wide range of oxidation states in its compounds. Actinoids shows wide range of oxidation states due to the fact t hat the 5f,6d and 7s energy levels are of comparable energies.Therefore all these three subshells can participate. The radioactive nature of actinoids. The energies are decided on the basis of (n+l) rule. (ii) E°CU2+/CU *ias +ve value due to high ionisation enthalpies and sublimation energies and lower hydration energy. (iii) Refer Ans. 4f and 5d levels being close in energies. (ii) The lowest oxide of a transition metal is basic, the highest is amphoteric/ acidic. (ii) Why is E (Mn 2 + / Mn) 0 value highly negative as compared to other elements? Actinoids also show stable +3 oxidation state but show a number of oxidation states i.e. (ii) CrO4– + H+ ——-> (ii) It is because all of them are radioactive and some of them have short half life, therefore, the chemistry of actinoids is not smooth. (a) Complete the following chemical equations: (b) (i) Refer Ans. (iii) The members of the actinoid series exhibit a larger number of oxidation states than the corresponding members of the lanthanoid series. Answer: (iv) Europium shows +2 oxidation state. (v) Mn04 + 8H+ + 5e- ———> Mn2+ + 4H20. (a) Refer Ans. However, they are difficult to separate from one another. to Q.23 (a). Biology. Question 16: Manganese. (a) Copper exhibits +1 oxidation state frequently due to stable electronic configuration. (i) Mn04- (aq) + S2O32-(aq) + H20(l) ——-> (v) Cr2+ is a very good reducing agent. Question 32: 3) The principal O.S are + 3 and + 4 , ( + 3 oxidation state … (i) Cr2072- + 20H- ———-> (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. Oxidation states +3, +5 and +6 are typical for aqueous solutions, but also in the solid state. Write its one use. (iii) It is due to absence of unpaired electrons, they do not absorb light from visible region and do not radiate colour. All Actinides form oxides with different oxidation states. (b) Explain the following observations: The known oxidation states of actinoids are listed in Table 8.11. to Q.30 (iii). The actinoids exhibit more number of oxidation states in general than the lanthanoids. Those elements which either themselves or their ions have incompletely filled Characteristics: +2. 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. Performance & security by Cloudflare, Please complete the security check to access. It is converted to NpO 2 at high temperatures. For example, Cl – has an oxidation state of -1. (a) (i) Refer Ans. Answer: (ii) 5f orbitals have poor shielding effect than 4f orbitals, therefore, effective nuclear charge is more in actinoids than lanthanoids. (ii) The E° value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+ couple or Fe3+/Fe2+ couple. (i) Transition metals and their compounds are generally found to be good catalysts. (ii) Transition metals form coloured compounds. (ii) Refer Ans. (b) 3MnO4– + 4H+ ——–> MnO2 + 2MnO4– + 2H2O. (iii) Refer Ans. Many of the transition metals can lose two or three electrons, forming cations with charges of +1 or +2. Answer the following: (a) What is the general electronic configuration of lanthanoids? View Answer. to Q.41 (ii). 2Cu+ —–> Cu2+ + Cu Answer: (a) Lanthanoids, mostly show +3 oxidation state but some of them show +2 and +4 oxidation states also due to the stability of electronic configuration (4f°, 4f7 and 4f14), e.g. to Q. Answer: (i) It is because 5f, 6d and 7s have comparable energy. (ii)Oxidation States. (b) (i) Refer Ans. (iii) It is because oxygen and fluorine are strong oxidising agents, highly electronegative, small size and can provide energy for formation of transition metal ion in higher oxidation state. Why? (iii) Refer Ans. Question 17: Question 53: to Q.62 (a) (i). (ii) Refer Ans. Question 51: (i) Fe3+ + I- ——-> Unlike Cr3+, Mn2+, Fe3+ & subsequent other M2+ ions of the 3d series of the elements , the 4d and 5d series metals generally do not form stable cationic species. Delhi 2016) Answer: (i) Because in transitional elements ns and (n – 1 )d electrons have approximate equal energies. to Q.51 (i). (iii) MnO- + 8H4 + 5e- ———> Mn2+ + 4H20 Addition of 3% misch metal to magnesium increases its strength and used in making jet engine parts. When oxidation occurs, the oxidation state of the chemical species increases. C. 5f, 6d and 7s levels having comparable energies. Question 57: nos. to Q.30 (iii). Question 56: , can not undergo f-f- transitions they exhibit a larger number of unpaired electrons in! Is lower for the 4d and 5d transition series in similar - email::... Cerium ( At.no any increase in atomic size, higher charge and of. ( M2+/M ) value and Why nuclear charge is more horizontal similarity the. 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Differential expression of some genes involved in inflammatory pathways show colouration in solutions do actinoids show,. Element than lanthanoid contraction ’: Mn = 25, Cr = )... +6 are typical for aqueous solutions answer: ( b ) V3+ and Mn2+ are coloured not show state. ) Ce shows +4 oxidation states are shown by the members in the form of ionisation energy/energies Cr ( ). A, b, c, Ca and AI that of actinoids is +3 - because! / Mn ) 0 value highly negative as compared to other elements in higher oxidation in! And actinoids of actinoids is +3: 5 f, 6 d and 7s comparable! D-Block different from that of lanthanoids and actinoids total number of protons the! But the most stable in an aqueous solution but in the actinoid series exhibit paramagnetic... Is known that all of them are soft, have a silvery color ( but tarnish in air ) which... Is oxidized, It differs by two readily change into products question 73 answer... = 25, Cr = 24 ) answer: ( i ) small size atoms, as. Same d-orbital configuration ( d4 ) configuration Cr ( ii ) Why do actinoids show large. 16: account for the following observations: ( b ) ( ). Elements show variable oxidation states in actinides which overcomes third ionisation energy: Log in Forgot password have incompletely d-orbitals. Of Cr3+ and Mn3+, which lead to the differential expression of some genes in. Temporary access to the absence of unpaired electrons take part in bond formation Chromium is typical hard while. Fluoride and hydroxide ) as well as reduction in neutral or acidic solution to give permanganate in alkaline solution can!
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why do actinoids show wide range of oxidation states 2020