Question

How many electrons can be present in an atom having three principal
energy levels? *

Answer 1

18 electrons

Step-by-step explanation:

The five d orbitals can hold up to 10 electrons. Thus, the third level holds a maximum of 18 electrons: 2 in the s orbital, 6 in the three p orbitals, and 10 in the five d orbitals.

Answer 2

18 electrons

Step-by-step explanation:

The third principal energy level has one s orbital, three p orbitals, and five d orbitals, which can each hold up to 10 electrons. This allows for a maximum of 18 electrons. The fourth and higher levels have an f sublevel in addition to the s, p, and d orbitals.