The elements Z (atomic number) = 117 and 120 have not yet been discovered. In which group would you place these elements?

I tried to write their electronic configurations but it was too tedious and I do not remember the Aufbau principle to that extent ($\ce{5g, 6f}$...).

Is there any quicker way to solve this question?

  • 1
    $\begingroup$ One way you can go about doing this is learning the number of elements present in each period. The first period has 2, the second and the third have 8 each, the fourth and the fifth have 18 each, the sixth and the seventh have 32 elements each. Since the noble gases are present at the end of the period, you can now calculate their atomic numbers which are - 2, 10, 18, 36, 54, 86 and 118 (2+8=10, 10+8=18, 18+18=36, 36+18=54, 54+32=86, 86+32=118). Now you can place Z-117 in the Halogen group(17) just before the noble gas, and 120 in the Alkaline earth metals group(2). $\endgroup$ – Parth Chauhan Aug 26 '18 at 6:42
  • 6
    $\begingroup$ 117 has been made years ago, and it even has a name since 2015. $\endgroup$ – Karl Aug 26 '18 at 9:02
  • 1
    $\begingroup$ Ditto element 118. $\endgroup$ – Oscar Lanzi Aug 26 '18 at 9:38
  • 4
    $\begingroup$ Elements 119 and 120 should be more or less typical alkali and alkaline earth metals. But the increasingly important relativistic effects make things more complicated. There is actually a wikipedia article about elements 119 and beyond: en.wikipedia.org/wiki/Extended_periodic_table $\endgroup$ – Feodoran Aug 26 '18 at 11:02
  • 1
    $\begingroup$ You would place Z = 120 in the second group, Alkali Earth Metals, as that element completely fills the 8s orbital. Z = 117 is Tennessine, which is a group 17 Halogen and has already been discovered. $\endgroup$ – JERRY_XLII Sep 17 at 4:43

Browse other questions tagged or ask your own question.