An atom of oxygen has eight protons
in its nucleus. Which energy level diagram shows
the correct electronic configuration for oxygen?
We’ve been given five energy level
diagrams labeled from (A) to (E). We need to identify which diagram
shows the correct electronic configuration for oxygen. And we are told in the question
that oxygen has eight protons. So a neutral atom of oxygen will
also have eight electrons. We can immediately eliminate answer
choice (E) as the diagram shows that oxygen has 10 electrons, rather than eight.
The other answer choices have the
correct number of electrons, but the electrons aren’t necessarily in the correct
energy levels. Each energy level has a different
maximum number of electrons. K is two, L is eight, M is 18, and
N is 32. The maximum number of electrons
found in energy level K is two. Thus, answer choices (C) and (D)
must be incorrect. Additionally, electrons fill the
lowest energy level first, which is K. So two of oxygen’s electrons will
be found in energy level K. And the remaining six will be found
in the second lowest energy level L. As answer choice (A) has an
electronic configuration of 2,6, it is the correct answer. The energy level diagram which
shows the correct electronic configuration for oxygen is answer choice (A).