Many people have wondered what helium is. It has no color and no odor, and when a balloon is filled with it, the balloon goes up instead of down!
Helium is a chemical element, one of the basic building blocks of matter. So we can’t make helium at home by mixing other elements together. In our everyday experience, helium is a gas. The tiny particles that make it up are always moving around, bouncing off one another and off other objects. Helium is lighter than the other gases that make up the air around us, which is why a helium balloon rises into the air. When a balloon full of helium is held on a string, Earth’s gravity pulls harder on the surrounding air than it does on the balloon. So that air is always slipping down under the balloon, pushing it upward.