Oxygen itself doesn't have a positive or negative charge. It's a neutral atom.

Here's why:

* Atoms are neutral: Atoms have an equal number of protons (positively charged particles) and electrons (negatively charged particles).

* Oxygen's structure: Oxygen has 8 protons and 8 electrons, making it electrically neutral.

However, oxygen often gains a negative charge in chemical bonds. This is because oxygen is highly electronegative, meaning it strongly attracts electrons.

In a covalent bond (where atoms share electrons), the shared electrons spend more time closer to the oxygen atom, giving it a partial negative charge (represented as δ-). The other atom involved in the bond then has a partial positive charge (represented as δ+).

So, while oxygen itself is neutral, it often has a partial negative charge in molecules.