Oxygen

Oxygen is one of the most important elements on earth. It is a colorless, odorless gas that makes up about one-fifth of the air around us. Every breath we take brings oxygen into our lungs, which our bodies use to make energy. Without it, humans, animals, and most plants could not survive.

Oxygen’s symbol is O and its molecule in the air is written as O₂, which means each oxygen molecule is made of two oxygen atoms. It was discovered in the 18th century by scientists who noticed that air had a part that made fire burn more strongly and helped animals stay alive. Today, we know that oxygen is part of many natural processes on Earth.

In living things, oxygen plays a key role in respiration. This is the process where cells use oxygen to change food into energy. When we breathe in, our lungs take in oxygen from the air. The oxygen then travels through the blood to every part of the body. When we breathe out, we release carbon dioxide, another gas that plants later use in photosynthesis.

Oxygen also helps things burn. When you see fire, oxygen is one of the invisible ingredients that keeps it going. If there is no oxygen, a flame goes out. This same process happens inside our bodies, where oxygen ‘burns’ food slowly to release energy, but without producing fire.

In nature, oxygen is not only in the air. It is part of water (H₂O), rocks, and many minerals. Most of the oxygen on Earth is locked inside these solid materials. Green plants and algae produce new oxygen every day through photosynthesis, using sunlight to turn carbon dioxide and water into sugar and oxygen. This is how the air stays fresh and balanced.

People use oxygen for many helpful purposes. In hospitals, oxygen tanks help patients who have trouble breathing. Divers and astronauts carry oxygen tanks because they go to places where normal air is missing. Industries also use oxygen in welding, rocket fuel, and water treatment. Oxygen reminds us how deeply life depends on air, plants, and the natural balance of our planet.