Valence electrons are contained in the ____ shell.

• A. Inner
• B. Outermost
• C. Middle
• D. Nucleus

Answer: (B)

Valence electrons are the electrons in the outermost electron shell of an atom. They’re the ones that participate in bonding—sharing, transferring, or pooling electrons with other atoms—so they determine how the atom interacts chemically. The inner shells are filled and held more tightly by the nucleus, so they don’t typically take part in bonding. The nucleus itself isn’t an electron shell, so it isn’t involved in where valence electrons reside. While there are multiple shells in larger atoms, the key point is that the valence electrons occupy the outermost shell, which is why that shell is described as the valence shell.