How to locate the position of element with atomic number 120 which is not yet discovered ?

1 Answer
Sep 4, 2017


You use the order of filling orbitals and your knowledge of the Periodic Table to locate Element 120.


The known elements

The last known element in the Periodic Table is Element 118, #"Og"# (oganesson).

(From Fotolia,com)

It is in the lower right-hand corner of the Periodic Table, at the end of Period 7 and the bottom of Group 18.

It is the last element in the #"p"# block, so its electron configuration ends in #"7p"^6#.

Where is element 120?

We use the order of filing atomic orbitals.

Energy levels
(Adapted from Wikibooks)

It shows that the next electrons will go into the #"8s"# orbital.

The #"s"# block is at the left-hand side of the Periodic Table, and the #"8s"# orbital can hold two electrons.

That’s just enough electrons to get us from #"Og"# to element 120.

Periodic Table

You will find it under radium (at. no. 88), so it should be an alkaline earth metal.