Final answer:
An sp2 hybridized oxygen atom has four valence electrons in three sp2 orbitals, with two electrons in lone pairs and two in the sp2 and p orbitals involved in bonding.
Step-by-step explanation:
An oxygen atom that is sp2 hybridized will have four valence electrons occupying sp2 orbitals and two valence electrons occupying p orbitals. In sp2 hybridization, the one s orbital and two p orbitals mix to produce three sp2 hybrid orbitals, and one p orbital remains unhybridized. A lone pair of electrons occupies two of the sp2 orbitals, while the remaining sp2 orbital is used to form a sigma bond. The unhybridized p orbital is typically involved in pi bonding. As a result, the sp2 hybridized oxygen in molecules like formaldehyde (H₂C=O) uses two sp2 orbitals for its lone electron pairs, one sp2 orbital for sigma bonding with carbon, and the p orbital for pi bonding with carbon.