Atom X has 17 protons. How many electrons are in its valence shell (outermost energy level)?
A) 7
B) 3
C) 5
D) 10

Question

Quizplus · Accepted Answer

Atom X is a neutral atom, which means it has the same number of electrons as it does protons. The atomic number of X is 17, which means it has 17 electrons. The valence shell of an atom is the outermost energy level that contains electrons, and for many elements, including X, the valence shell can hold up to 8 electrons. To determine the number of electrons in X's valence shell, we look at its position in the periodic table. X is in group 17 (also known as the halogens), which means it has 7 valence electrons. Therefore, the answer is A) 7.

Atom X Has 17 Protons