# Exercise 2 | Quantum Theory and Atomic Structure

How many electrons can be specified by the following combinations of quantum numbers?

- n = 2

- n = 3, l = 2

- n = 3, l = 1, ml = 0

- n = 4, l = 2, ml = -1, ms = ½

- n = 2 ⇒ 2 subshells: 2s and 2p ⇒ 4 orbitals
⇒ 4 x 2 e- = 8 e-

- n = 3, l = 2 ⇒ 1 subshell: 3d ⇒ 5 orbitals
⇒ 5 x 2 e- = 10 e-

- n = 3, l = 1, ml = 0 ⇒ 1 subshell: 3p + only 1 orbital (ml = 0)
⇒ 1 x 2 e- = 2 e-

- n = 4, l = 2, ml = -1, ms = ½ ⇒ 1 subshell: 4d, 1 orbital (ml = -1), 1 e- (ms = ½)
⇒ 1 e-