Question

Use the periodic table to correctly describe the arrangement of electrons in an oxygen atom. Check all of the boxes that apply.

The electron configuration is 1s22s22p2.

The electron configuration is 1s22s22p4.

The electron configuration is 2s22p6.

There are valence electrons in the 1s-, 2s-, and 2p-orbitals.

There are valence electrons in the 2s- and 2p-orbitals.

There are valence electrons in the 2p-orbitals only.

Answer 1

Correct choices:

- The electron configuration is 1s2 2s2 2p4. (✔)
- There are valence electrons in the 2s- and 2p-orbitals. (✔)

Why: Oxygen has Z = 8, so its electrons fill 1s2 2s2 2p4. Valence electrons are those in the highest principal energy level (n = 2), so the 2s and 2p electrons are valence. The other statements are incorrect.