Which actinide element has an electron configuration of [Rn] 7s² 5f¹³?

The correct answer is Mendelevium (Md), which has the electron configuration of [Rn] 7s² 5f¹³. This configuration indicates that Mendelevium is in the actinide series and occupies the f-block of the periodic table, specifically having a total of 13 electrons in the 5f subshell.

Mendelevium is the element that comes after fermium (which has the configuration [Rn] 7s² 5f¹²) and is characterized by this specific electron filling of the 5f orbital. The notation [Rn] represents the electron configuration of Radon, which serves as the core configuration-up to the completion of the noble gas, followed by the filling of the 7s and 5f orbitals.

The other elements listed either have fewer or different electron configurations that do not match the specified one. Understanding how to read and write electron configurations helps identify the correct placement of elements in their respective series and subshells within the periodic table.