Periodic Table and Its Properties Exercise # 4

PERIODIC TABLE AND ITS PROPERTIES Exercise # 4 [Subjective Type Questions] 1. Describe the term penetration as it applies to electronic configuration. The properties of which one of the following elements are most modified by penetration, and the properties of which one are least modified : Zn, Ca, Br, H ? 2. Why the size of atom decreases from scandium to vanadium, remains almost unaltered from chromium to copper but increases from copper to zinc ? 3. Why is the decrease in size between Li and Be more pronounced than that between Na and Mg or K and Ca? 4. Why the Ist ionisation enthalpy of potassium is less than that of copper but the reverse is true for IInd ionisation enthalpy ? 5. The ionisation enthalpies of the coinage metals fall in the order Cu > Ag < Au. Why ? 6. With reference to Modern periodic table, identify : (a) an element that is in group  A (group 13) and 3rd period. (b) the second transition element of fourth period. (c) the group which accommodates lanthanides and actinides. (d) the elements of 15th group which show metallic as well as non-metallic behaviour. 7. An element belonging to 3d series of Modern periodic table has spin magnetic moment = 5.92 B.M. in +3 oxidation state. Determine the atomic number and name of the element. Also determine the period, block and group of the element in Modern periodic table. 8. Inspite of both O2– and F– having stable electronic configuration of Neon, the formation of F–(g) from F(g) is exothermic where as that of O2–(g) from O(g) is endothermic. Why ? 9. First and second ionisation enthalpies of Mg are 720 kJ/mol and 1440 kJ/mol respectively. Calculate the % of Mg+ ions, if one gram of Mg(g) absorbs 50 kJ of energy. (Given : Atomic mass of Mg = 24 amu.) 10. The second ionization enthalpies (in kJmol–1) of some elements of 4th period of Modern periodic table are : Ca Sc Ti V Cr Mn 1145 1235 1310 1365 1592 1509 Account for the trend in values. 11. The electron gain enthalpy of a hypothetical element ‘A’ is –3 eV per atom. How much energy in kCal is released when 10 g of ‘A’ are completely converted to A– ions in gaseous state ? (Take : 1 eV per atom = 23 kCal mol–1, Molar mass of A = 30 g) 12. For the gaseous reaction K + F  K+ + F–, H was calculated to be 18.4 kCal/mol under conditions where the cations and anions were prevented from combining with each other. The ionization enthalpy of K is 4.3 eV/atom. What is the electron gain enthalpy of F (in eV) ? (Take : 1 eV/atom = 23 kCal/mol) 13. In Modern periodic table, the increasing order of reactivity among group 1 elements is Li < Na < K < Rb < Cs whereas that among group 17 elements is F > Cl > Br > I. Explain. 14. "CO is acid anhydride of Formic acid (HCOOH) and N2O is acid anhydride of Hyponitrous acid (H2N2O2)". State whether true or false. Comment. 15. The acidic strength of hydrohalic acids (HX) increases on moving down the group in Modern periodic table, while it decreases for perhalic acids (HXO4). Explain. 16. Which of the following compounds are found to exist ? BiF5, PbO2, SnCl2, Tl2O3, PbI4, As2O3 17. If 0.5 mole of gaseous non-metallic X– anions requires 806.4 kJ energy to get completely converted into gaseous X+ ions, then calculate Pauling's electronegativity of the element X. Assume that element X has negative value of electron gain enthalpy. Use Avogadro's No. = 6 × 1023 and 1eV = 1.6 × 10–19 J. Hint : [Pauling's electronegativity = Mulliken's Electronegativity ] 2.8 18. Electronegativity values on Mulliken scale for two different elements are given as 7 and 1.4 respectively. If bond is formed between them, then calculate the percentage ionic character of the bond between them, using Hanny Smith formula. 19. Write the chemical formula of following compounds/ions 20. (1) ferric sulphate (2) Magnesium phosphite (3) Nickel dithiosulphate (4) Cadmium nitrite (7) Nickel bisulphate (5) Calcium metaborate (8) Arsenous oxide (6) Mercuric iodide (9) Lead formate (10) Aluminium acetate (13) Cuprous sulphide (16) Ammonium hyponitrite (11) Sodium dichromate (14) Metaphosphate ion (17) Aluminium hydrogenphosphite (12) Potassium cyanide (15) Hydrogen peroxide Give the chemical formulae for (a) Potassium pyrosulphite (b) potassium hydrogenpyrophosphite (c) Barium permanganate (d) Scandium trihydrogenpyrosilicate (e) Sodium strontium aluminium pyrosilicate (f) Vanadium (III) Phosphate 21. 22. Give the formulae for (a) Magnesium Nitride (b) Barium fluoride (c) Iron (III) sulphide (d) Strontium hydride (e) indium (I) chloride (f) Rubidium super oxide (g) Caesium lodide (h) Calcium phosphide (i) Stannous chloride (j) Potassium ozonide (k) chromium (III) oxide (l) Mercurous chloride (m) Potassium peroxide (n) Xenon tetraoxide Which of the following formulae are wrong ? Write the correct possibilities? (1) NO2 (2) AlO2 (3) CO2 (4) Sil2 (5) SnO (6) PbO2 (7) FeO (8) MnO2 (9) V2O5 (10) K3I (11) Cr2O7 (12) BiF5 (13) PbO2 (14) Ti2O5 (15) CuF4 (16) AgF3 (17) ZnS (18) K2O (19) K2O2 (20) K2O5 (21) K2Se (22) KSe3 (23) KI3 (24) KI (25) Ni(CN)2 (26) FeO4 (27) HeO4 (28) HeS (29) H2S (30) BiO2 (31) SnS2 (32) SnS (33) Sn2S3 (34)YCl3 (35) CdF3 (36) XeF7 (37) FeO2 (38) CrO3 (39) KO2 (40) AgCl (41) SiH4 (42) ZrCl3 (43) Fe2O3 (44) NiCl5 (45) KO3 (46) XeO4 (47) Rb(CN)3 PERIODIC TABLE AND ITS PROPERTIES 23. 24. Name of the following (a) XeF6 (b) SCl2 (g) N2O4 (h) XeO4 (m) Tl2O3 (n) CsO3 (s) UO2 (t) PbH4 Give the formulae for (a) Tantallum (III) nitride (d) Barium azide (g) Xenon trioxide (j) Beryllium telluride (m) Bismuth (III) oxide (c) SO2 (i) Li3N (o) Zn(CN)2 (d) SO3 (j) RbN3 (p) LiH (e) NO2 (k) MnO2 (q) CH4 (b) Gold (III) fluoride (e) strontium nitride (h) Radium silicide (k) Potassium ozonide (n) Gallium selenide (f) N2O5 (l) BaO2 (r) NaAu (c) Iron (II) iodide (f) Caesium peroxide (i) Lithium hydride (l) Chromium (III) sulphide (o) Aluminium arsenide 25. Group the elements, whose atomic numbers are given below, into various blocks in Modern periodic table : 19, 25, 31, 38, 42, 54, 64, 105 26. What is the name given to the elements which represent the properties of lower elements of their respective group in Modern periodic table ? These elements belong to which period in Modern periodic table ? 27. A particular atom having atomic number between 22 to 30 has spin magnetic moment equal to 1.73 B.M. Then find the atomic number of the element which is just below it in the Modern periodic table. 28. Compare the screening effect of a d-electron with a f-and a p-electron. 29. Arrange the following in order of atomic/ionic radius : (i) N3–, P3–, As3– (ii) Cr, Mn, Fe (iii) Cu, Zn 30. Why the Ist ionisation enthalpy of nitrogen is higher than oxygen and opposite is true for second ionisation enthalpy ? 31. Compare qualitatively the first and second ionization potentials of copper and zinc. Explain the observation. 32. The alkali metals (A) and coinage metals (B) seem to have the same outer electronic configuration ns1 (n = principal quantum number of outermost shell), but group (B) elements are more stable than group (A) elements. Explain. 33. Na+ has higher value of ionisation enthalpy than Ne, though both have same electronic configuration. Explain. 34. Give the variation of : (a) Ionisation enthalpy in Group 14 of Modern periodic table. (b) Pauling's electronegativity in Group 13 of Modern periodic table. 35. The ionisation enthalpies of atoms A and B are 400 and 300 kCalmol–1 respectively. The electron affinities of these atoms are 80 and 90 kCalmol–1 respectively. Determine which of the atoms have higher electronegativity on Pauling scale. (Take : 23.1 × 5.6 = 130). 36. Calculate the % ionic character in AB molecule according to Hanny Smith formula, if bond enthalpy (in kCal/mol) of AB molecule is 6 units. AA molecule is 4 units. BB molecule is 1 unit. Take : 0.104 × 2 = 0.2. 37. Electrons of which subshell do not participate in bonding due to inert pair effect ? 38. Arrange the following in correct order of reducing capacity : Ge2+ , Sn2+, Pb2+