Consider the n = 3 energy level in a hydrogen atom. How many electrons can be placed in this level?

A. 1

B. 2

C. 8

D. 9

E. 18

The rule for determining the number of electrons is 2(n^₂) The number of energy levels in represented in N. For example, on the third energy level, you would square 3 to get 9, and then multiply 9 by 2 to get 18. The third energy level can hold up to 18 electrons.