Atom X has 17 protons. How many electrons are in its valence shell (outermost energy level)?

Question

Quizplus · Accepted Answer

The valence shell of an atom is the outermost energy level that contains electrons, and the number of valence electrons is equal to the number of electrons in the outermost energy level. In the case of atom X, its atomic number is 17, which means it has 17 electrons. The first energy level can hold a maximum of 2 electrons, and the second level can hold a maximum of 8 electrons. This leaves 7 electrons in the third energy level, which is the valence shell. Therefore, the answer is C.

Atom X Has 17 Protons