Oxygen

Imagine the air is like a giant invisible blanket covering our planet. Oxygen is a super important part of that blanket! It's a special gas that makes up about 20% of the air.

That means for every five breaths you take, one is mostly oxygen. It's a chemical element, which is like a basic building block for everything in the universe. It's also very good at joining up with other things, like when iron rusts or water forms.

Why do we need oxygen? Because our bodies use it to get energy from the food we eat! It's like a tiny engine inside our cells. When we breathe in oxygen, our bodies use it to break down food and turn it into energy that helps us run, jump, and play. As a bonus, when our bodies use oxygen, they make carbon dioxide, which is what we breathe out. Plants love to use that carbon dioxide!

Oxygen isn't always just the gas we breathe (that's called O2). Sometimes, three oxygen atoms can stick together to make a different gas called ozone (O3). Ozone is really special because it floats high up in the sky and acts like a giant sunscreen, protecting us from the sun's strongest rays. But down on the ground, ozone can be a bit of a troublemaker and is part of pollution.

People have known about oxygen for a long, long time, but it was tricky to figure out exactly what it was. Scientists like Carl Wilhelm Scheele and Joseph Priestley studied it a lot. Later, Antoine Lavoisier realized that oxygen was a brand new element and understood how important it was for things like fire and breathing. It took clever minds to discover this invisible, life-giving gas!