In the ground state of a neutral atom, the last electron enters a subshell characterized by the quantum numbers n = 3 and l = 2 . If this subshell contains exactly 3 electrons, the atomic number of the element is:

Step-by-step solution

The quantum numbers n = 3 and l = 2 correspond to the 3 d subshell. Since the subshell contains exactly 3 electrons, the electronic configuration ends in 3 d ³ . According to the Aufbau principle, the 4 s subshell is filled before the 3 d subshell. The full ground state electronic configuration of the atom is: 1 s ² 2 s ² 2 p ⁶ 3 s ² 3 p ⁶ 4 s ² 3 d ³ Summing the number of electrons gives the atomic number Z : Z = 2 + 2 + 6 + 2 + 6 + 2 + 3 = 23 Answer: 23