Hence the fourth period consists up of 18 and not 8 elements. Q.14 Predict the formulae of the stable binary compounds that would be formed by the following pairs of elements: (a) SiO2 (b) AlBr3 (c) Cal2 (d) Uuq F4 (e) (Ubn)O. Q.15 Consider the element N, P, O and Sand arrange them in order of (a) Increasing first ionization enthalpy (b) Increasing negative electron gain enthalpy (c) Increasing non-metallic character. w Rb OST
Thus 10 elements are built up by the filing of 3d orbitals. & Antimony (Sb) and Bismuth (Bi) belong to group 15. How much energy in kJ is released when 3.55 g of chlorine is converted completely into Cl– ion in the gaseous state. Thallium (T1) belongs to group 13. The first period starts with the filling of the lowest level (1s) and has thus the two elements – hydrogen (1s1) and helium (1s2) when the first shell (K) is completed. Therefore its IE, However in case of Mg, Si and P, through their IE, The first electron in both cases has to be removed from the 3s orbital but nuclear charge of Na is less than that of Mg. After the removal of first electron from Na, the electronic configuration of Na, Q.25 The electron gain enthalpy of chlorine is –349 kJ mol, Energy released when 1 mole (= 35.5g) of chlorine atoms change completely with Cl, Q.26 The amount of energy released when 1 × 1010 atoms of chlorine in vapour state are converted to Cl, Calculate the electron gain enthalpy of chlorine atom in terms of kJ mol, Each successive period in the periodic table is associated with the filling up of the next higher principal energy level (n = 1, n = 2 etc). Its IE2 >>E1, meaning it can lose one electron readily but not the second. It lies in the 4th period and in the 3rd group. They form unipositive ions M+ by losing one electron from their valence shells. Filling up of the 4f orbital s begins with cerium (Z = 58) and ends at lutetium (Z = 71) to give the 4f inner transition series which is called the lanthanide series. Whereas N is 1s2, 2s2 2p1x 2p1y 2p1z (exactly half- filled). (d) The block indicates value of azimuthal quantum number (1) for the last subshell that received electrons in building up the electronic configuration. Q.28 The increasing order of reactivity among group 1 elements is Li < Na < K < Rb < Cs whereas that among group 17 elements is F > CI > Br > I. Therefore, it is easier to remove one electrons from O atom F, due to increased nuclear charge, has more IE than either O or N. Q.17 How will you explain the fact that first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium? (d) Group I, if we include Hydrogen in it. Lanthanides and actinides are placed in separate rows at the bottom of the periodic table (i) to save space (ii) to keep elements with similar properties in a single column and (iii) because their antepenultimate 4 f and 5 f orbitals are filled respectively. Q.24 The IE1, of Mg is higher than that of Na. 36) = 1s2,2s22p6,3s23p63d10,4s24p6. Variation of Atomic radii across a period : Atomic radii decrease with the increase in the atomic number in a period. Q.39 Which of the following atoms would be paramagnetic? It has no tendency to lose electrons [as is clear from its high IE1 and its higher IE2], nor can it gain electron [positive value of electron gain enthalpy- energy has to be absorbed to gain or add an electron]. Q.25 In which of the following compounds does the ratio of the anion size of cation size has the lowest value? Explain the reason for this arrangement. It is Lithium. Physical differences between metals & Non – metals. d- block consists up of group 3 – 12, called transition elements. Ne and Na+ is affected by. The statement is wrong. Q.4 Explain why ionization enthalpies decreases down a group of the Periodic Table. Its IE, Q.3 The electronic configuration of an element is 1s, Q.7 Argon has atomic number 18 and belongs to 3, Q.13 Predict the position of the element in the periodic table satisfying the electronic configuration (n–1)d, Q.17 Arrange the following ions in order of decreasing ionic radii : Li, Q.19 Al atom loses electrons successively to form Al, Q.25 Give four examples of species which are isoelectronic with Ca, (i) The have got the general configuration of the valence shell ns, (i) The valence shell electronic configuration of p block elements in ns, As seen from the electronic configuration of K and K, Cl has higher electron affinity than F. This is due to small size of fluorine.