What is the octet rule primarily concerned with?

The octet rule is primarily focused on how atoms bond to achieve full outer electron shells, leading to greater stability. According to the octet rule, atoms tend to gain, lose, or share electrons in order to have eight electrons in their valence shell, mirroring the electron configuration of noble gases. This rule explains the behavior of many elements during chemical bonding.

For instance, when a sodium atom loses one electron, it achieves a full outer shell similar to neon, promoting stability. Similarly, chlorine gains an electron to reach a stable configuration akin to argon. The emphasis on bonding for achieving stable electron arrangements illustrates why option B is the most appropriate choice.

The other options do not capture this core principle; while crystalline structures, electron energy levels, and types of reactions are essential concepts in chemistry, they do not relate specifically to the disposition of electrons as dictated by the octet rule.