How Many Electrons Can the Fourth Energy Level Hold? 32
The fourth energy level (n=4) can hold a maximum of 32 electrons. This is determined by the formula 2n², where n is the principal quantum number. For n=4, the calculation is 2 × 4² = 2 × 16 = 32.
Why 32 Electrons?
Energy levels are divided into subshells (s, p, d, f), each with a fixed capacity. For the fourth level, the subshells are 4s, 4p, 4d, and 4f. Their capacities are:
- 4s: 2 electrons
- 4p: 6 electrons
- 4d: 10 electrons
- 4f: 14 electrons
Adding these gives 2 + 6 + 10 + 14 = 32 electrons. The formula 2n² works because the number of subshells in a level equals n (here, four subshells), and the total orbital count is n² (16 orbitals), each holding two electrons IUPAC. In practice, atoms fill these subshells in a specific order (the Aufbau principle), so the fourth level is not fully occupied until very heavy elements like those in the actinide series. For example, the element oganesson (element 118) has a filled 4f subshell as part of its electron configuration.
Key Takeaways
- The fourth energy level holds a maximum of 32 electrons, calculated by 2n² for n=4.
- This total comes from the s (2), p (6), d (10), and f (14) subshells within the level.
- The 2n² rule applies to any principal energy level, with n=1 holding 2, n=2 holding 8, n=3 holding 18, and n=4 holding 32 electrons.
- In real atoms, the fourth level fills gradually across the periodic table, with the 4f subshell only appearing in lanthanides and actinides.
