Final answer:
An atom with seven electrons will have five electrons in the second energy level, as the first level (1s) can only hold two electrons. The remaining five occupy the 2s and 2p sublevels of the second energy level.
Step-by-step explanation:
If an atom has seven electrons, the number of electrons located in the second energy level can be determined by following the electron configuration rules according to the quantum model. For the first energy level (n=1), a maximum of two electrons can be accommodated. Once the first level is full, additional electrons will fill the next energy level. In the case of an atom with seven electrons, like nitrogen (N), the electron configuration would be 1s² 2s² 2p³. This means that after the two electrons fill the 1s sublevel, the remaining five electrons are located in the second energy level, occupying the 2s and 2p sublevels.
Using nitrogen as an example, the second energy level will therefore have a total of five electrons, which includes two electrons in the 2s suborbital and three electrons in the 2p suborbital. The quantum model of atomic structure aids in understanding this configuration, as it details the distribution of electrons across different energy levels and sublevels within an atom.