We breathe O2 (molecular oxygen), not O (atomic oxygen).
Normal human breathing involves inhaling air that is a mixture of gases, primarily nitrogen, and importantly, approximately 21% molecular oxygen, which is represented as O2.
The following table summarizes the difference between O and O2:
| Term | Description |
|---|---|
| O | Atomic Oxygen; a single oxygen atom. Highly reactive and not found in stable, breathable air. |
| O2 | Molecular Oxygen; two oxygen atoms bonded together. The form of oxygen essential for human respiration. |
Here are key points to consider about how breathing works:
- Air Composition: The air we breathe contains about 21% O2, the primary gas our bodies use for respiration.
- Oxygen Uptake: When we inhale, oxygen (O2) is transferred from the air into our bloodstream via the lungs.
- Cellular Respiration: Our cells use this O2 to convert glucose into energy, producing carbon dioxide (CO2) as a waste product.
- Molecular Form Importance: The O2 molecule is stable enough to be present in our atmosphere, unlike the highly reactive O atomic form, and to be taken up by our cells and used for respiration.
Based on the reference, we know that normal breathing uses ambient air with 21% oxygen (O2) concentration. This information highlights the importance of O2 for respiration.
