Which element is represented by the configuration [He] 2s^2 2p^3?

The electron configuration [He] 2s² 2p³ corresponds to the element arsenic. The notation [He] indicates that the configuration starts from the electron configuration of helium, which has two electrons. The 2s² indicates that there are two electrons in the 2s orbital, and the 2p³ indicates that there are three electrons in the 2p orbital.

When we add these electrons together, we find a total of 5 electrons in the second shell (2 in the 2s and 3 in the 2p), resulting in an atomic number of 15. This atomic number corresponds to the element phosphorus, not nitrogen or any of the other options listed. Thus, with its total of 15 electrons, the element represented by this electron configuration is phosphorus.

For clarity on what each incorrect option represents:

• Nitrogen has an atomic number of 7 and a configuration of [He] 2s² 2p³.

• Boron has an atomic number of 5 and a configuration of [He] 2s² 2p¹.

• Oxygen has an atomic number of 8 with a configuration of [He] 2s² 2p⁴