The second shell of an atom can hold a maximum of eight electrons when filled to capacity. This is determined by the formula 2n², where n is the principal quantum number representing the shell level. For the second shell, n equals 2. Plugging this into the formula gives 2(2)² = 2(4) = 8.
The arrangement of electrons in shells follows a specific pattern: the first shell (n=1) can hold 2 electrons, the second shell (n=2) can hold 8 electrons, the third shell (n=3) can accommodate 18 electrons, and so forth, but the second shell is limited to eight as it is its maximum capacity. This capacity supports the stability of atoms, particularly those that make up most of the elements in nature, based on the octet rule which indicates that atoms are more stable when they have eight electrons in their outer shell.
Understanding this concept is crucial for grasping the fundamentals of atomic structure and chemical bonding.