Question

1. which principal energy level of the period 4 transition metals is being filled with electrons?

a. fourth
b. fifth
c. third
d. sixth

Explanation:

Step1: Recall electron - filling order

According to the Aufbau principle, for period 4 transition metals, the \(3d\) orbitals are being filled. The \(n = 3\) (third) principal energy level contains the \(3d\) orbitals.

Answer:

C. third