What is the maximum number of electrons that can occupy the n = 3 electron shell?

What is the maximum number of electrons that can occupy the n = 3 electron shell?

• A. 8
• B. 32
• C. 18
• D. 12

Answer: (C)

The maximum number of electrons in a shell is determined by 2n^2, since a shell with principal quantum number n contains n^2 orbitals and each orbital holds 2 electrons. For n = 3, that gives 2 × (3)^2 = 18 electrons. You can also add up the sublevels in that shell: s holds 2, p holds 6, and d holds 10, which totals 18. So the maximum number of electrons in the n = 3 shell is 18.

The maximum number of electrons in a shell is determined by 2n^2, since a shell with principal quantum number n contains n^2 orbitals and each orbital holds 2 electrons. For n = 3, that gives 2 × (3)^2 = 18 electrons. You can also add up the sublevels in that shell: s holds 2, p holds 6, and d holds 10, which totals 18. So the maximum number of electrons in the n = 3 shell is 18.