True or False: Stable atoms have completely filled outer electron shells.

The assertion that stable atoms have completely filled outer electron shells is indeed true. Atoms seek stability through achieving a full outer shell of electrons, which is generally associated with the noble gases in the periodic table. When an atom has a full outer shell, it tends not to react or bond with other atoms, resulting in a chemically inert state. This concept is rooted in the octet rule, which states that atoms tend to gain, lose, or share electrons to attain eight electrons in their outer shell, leading to greater stability.

While there may be exceptions and certain atoms can be stable with fewer than eight electrons in their outer shell, the fundamental principle holds that full outer electron shells contribute significantly to atomic stability. Thus, the statement regarding stable atoms having completely filled outer electron shells is accurate.