Final answer:
The total number of electrons that can be held in all the orbitals with main quantum number n=3 is 18, based on the formula 2n².
Step-by-step explanation:
The question asks about the total number of electrons that can be held in all orbitals with the principal quantum number n=3. The formula to calculate this is 2n², where n is the principal quantum number. In the case of n=3, the shell can hold a total of 2(3)2 electrons, which is 18. This n=3 shell consists of the 3s (2 electrons), 3p (6 electrons), and 3d (10 electrons) subshells, which cumulatively can hold up to 18 electrons. It's noteworthy that the filling of shells does not always follow a strict sequence; after the 3p subshell begins to fill, electrons can start to occupy the 4s subshell before the 3d subshell is completely filled.
The total number of electrons that can be held in all orbitals having the same principal quantum number n=3 is determined by the formula 2n². In this case, n=3, so the total number of electrons in the three possible subshells is 2(3)² = 18. This means that a fully filled n=3 shell can hold a maximum of 18 electrons. It's important to note that before the n=3 shell is completely filled, electrons may also begin to occupy orbitals in the n=4 shell.