Which element is indicated by the electron configuration [Kr] 5s^2 4d^7?

The electron configuration [Kr] 5s^2 4d^7 corresponds to an element whose valence electrons are specifically arranged to reflect its position in the periodic table. The notation begins with [Kr], indicating that the element has a core electron configuration equivalent to that of krypton, which includes 36 electrons. The next part, 5s^2, indicates that there are two electrons in the 5s subshell, and the 4d^7 denotes that there are seven electrons in the 4d subshell.

To determine which element this configuration represents, we must count the total number of electrons. Starting from krypton, which has 36 electrons, adding 2 from the 5s orbital and 7 from the 4d orbital brings the total to 45 electrons. This matches the atomic number of rhodium (Rh), which is 45.

Rhodium is located in group 9 of the periodic table and is a transition metal. Its electron configuration illustrates a common characteristic of transition metals, where the d subshell is being filled in addition to filling the outer s subshell. The configuration delineates an element that is capable of various oxidation states and was likely to participate in complex formation,