Electron Configuration Practice Test

The electron configuration [Rn] 7s² 5f⁷ corresponds to the element that has a total of 9 electrons in the 5f subshell, which places it within the actinide series of elements. To identify the element based on its electron configuration, it’s helpful to recognize that the actinides are located in the f-block of the periodic table, specifically in the period corresponding to the 5f subshell. The sequence follows the filling of orbitals based on the Aufbau principle, where 5f is filled after the 6d orbitals. Each element in the actinide series has a distinct number of electrons, and the one with the configuration of 5f⁷ is specifically Fermium (Fm). Fermium is known to have an atomic number of 100, which fits the configuration of having 9 electrons in the 5f subshell after Radon (Rn) core. This means that the provided answer does not correctly correspond with the configuration mentioned. To give context, Berkelium (Bk), which is the choice given, corresponds to [Rn] 7s² 5f⁷, indicating that it does not reflect the correct number of electrons in the