Which element is associated with the configuration [Rn] 7s² 5f⁹?

The electron configuration [Rn] 7s² 5f⁹ indicates that the element has filled the 7s subshell with two electrons and has nine electrons filling the 5f subshell. In the context of the periodic table, this configuration corresponds to an element located in the actinide series, where the f orbitals are being filled.

To analyze the configuration: the 5f subshell can hold up to 14 electrons, and since it has 9 electrons in this case, this positions the element as being relatively in the early part of the actinide series. The specific element with this configuration is Neptunium, which is not listed in the options; however, the placement of electrons leads us to Fermium (Fm), which follows Californium (Cf) in the sequence.

Due to the filling sequence and how elements are organized by increasing atomic number, the correct association with the configuration [Rn] 7s² 5f⁹ is indeed Fermium (Fm). This check of the periodic table clarifies that the answer aligns with the electronic structure provided.

If the configuration was incorrectly indicated or misinterpreted in its association with Berkelium (Bk), the answer would