Question

The model below shows a calcium atom.

An image has a mix of red and blue balls in its center and 4 concentric black rings around the center. The first ring from the center has 2 small green balls on it. The second ring has 8 small green balls on it. The third ring has 8 small green balls on it. The outermost ring has 2 small green balls on it.

How many electrons are in the third energy level?

2
8
18
20

Answer 1

8

The diagram shows the electron distribution for calcium (atomic number 20) as 2, 8, 8, 2 — so the third energy level has 8 electrons.