Textbook problem 1E.15

[Maggie Messer 1A]

For this textbook problem, can anyone explain to me why d is not Rf (rutherfordium) and instead Th (thorium)? thank you!

Which elements are predicted to have the following ground-state electron configurations of their atoms:

(d) [Rn] 7s^2 6d^2

[Jessica Cornelia Hongarta 1G]

Hey, so for this question, [Rn] 7s^2 6d^2, when you calculate for the total number of electrons, you'll get 90 (86+2+2=90). Since this is the ground-state electron configurations, you just need to find an element that has an atomic number of 90. In the periodic table, you'll see that the element with the atomic number of 90 is Thorium (Th). It's not Rutherfordium since the atomic number of Rf is 104.

Hope this helps!