Here's why:
* Neutral Atom: An oxygen atom has 8 protons (positive charge) and 8 electrons (negative charge). These charges balance out, making the atom electrically neutral.
* Oxidation States: Oxygen is highly electronegative, meaning it attracts electrons strongly. In compounds, it often gains electrons and forms a negative oxidation state, typically -2. This doesn't mean it has a permanent charge, but rather it's indicating the relative electron distribution in the compound.
Examples:
* Water (H₂O): Oxygen shares electrons with two hydrogen atoms, giving it a -2 oxidation state.
* Carbon Dioxide (CO₂): Oxygen shares electrons with carbon, again having a -2 oxidation state.
Ions: Oxygen can form an ion called oxide (O²⁻) by gaining two electrons. This ion has a -2 charge.
In summary:
* Oxygen atom: Neutral.
* Oxygen in compounds: Often has a -2 oxidation state.
* Oxide ion: -2 charge.
