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

What are inner-transition elements? Decide which of the following atomic numbers are the atomic numbers of the inner-transition elements : 29, 59, 74, 95, 102, 104

(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.