Final answer:
The element with the electron configuration [Kr]5s2 4d7 is a transition metal, not a nonmetal or a noble gas, as it has its last electron entering a d orbital as characteristic of transition metals.
Step-by-step explanation:
The element with the electron configuration [Kr]5s24d7 can be identified by its unique electronic structure. After referring to the periodic table and electron filling order (the Aufbau principle), it is apparent that this configuration corresponds to a transition metal. Transition metals are characterized by having their last electron enter a d orbital.
This particular electron configuration does not correspond to a nonmetal or a noble gas as neither have electrons populating d orbitals in this manner. Instead, this element is located within the d-block of the periodic table, which consists entirely of transition metals. These elements are known for their properties as metals, such as conductivity and malleability, distinguishing them from nonmetals and noble gases.
The condensed notation of an element's electron configuration often uses the [noble gas] notation to simplify the representation of core electrons, with the noble gas symbol representing the completed electron shell similar to that of a noble gas. Transition metals' electron configurations typically extend beyond the nearest noble gas configuration by adding electrons to the d orbitals.