I keep getting “Quantum numbers” questions wrong in Structure of Atom. What's the trap?
confusing the principal quantum number n (shell) with l (subshell).
The usual trap: confusing the principal quantum number n (shell) with l (subshell). How to avoid it: n = which floor, l = which room type, m = which room, s = spin up/down. Go back to the definition — four numbers (n, l, m, s) that pin down an electron's shell, subshell, orbital orientation and spin.
Key point
Quantum numbers
Common mistake
confusing the principal quantum number n (shell) with l (subshell).
Memory tip
n = which floor, l = which room type, m = which room, s = spin up/down.
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