. What are inner-transition elements Decide which of the following atomic numbers are the atomic numbers of the inner-transition elements : 29, 59, 74,

Best Answer

(i)         Inner-transition elements Inner transition elements (or f-block elements) include lanthanoids (Z = 58 to 71) and actioniods (Z = 90 to 103). These elements have incomplete f-orbital in penultimate shell of their atoms. 

(ii)        The electronic configuration of given atomic number are as

29 = [Ar] 4s¹ 3d¹⁰ (d-block element or transition element)

59=[Xe] 6s² 4f³ (f-blcok element or inner transition element)

74 = [Xe] 6s¹4f¹⁴5d⁵ (d-block element or inner transition element)

95 = [Rn] 7s² 5f⁷6d⁰ (f-block element or inner transition element)

102 = [Rn] 7s² 5f¹⁴ (f-block element or inner transition element)

104 = [Rn] 7s²5f¹⁴ 6d² (d-block element)

Thus, atomic number 29 (lanthanoid), 95 and 102 (actioniods) are included among inner transition elements.