Molecules

A molecule is made when two or more atoms stick together. Atoms can join in many ways to form different molecules. Water, sugar, and air are all made of molecules. Molecules are too small to see with your eyes. But they make up everything in our world.

How Molecules Form

Atoms join together by sharing or trading tiny parts called electrons. When atoms connect, they form a bond. Some molecules have only two atoms, like oxygen in the air. Others have hundreds or even thousands. The way atoms join changes what the molecule does.

A super close-up image showing tiny molecules on a surface.
A super close-up image showing tiny molecules on a surface. (L. E. Dinca et al. / Wikimedia Commons)

Molecules Around Us

Water is the most famous molecule. It is made of two hydrogen atoms and one oxygen atom. The air we breathe has molecules of oxygen and nitrogen. Sugar, salt, and plastic are all made of molecules too. Your body is made of trillions of different molecules working together.

Fun Facts

  • One drop of water has more molecules than there are stars in our galaxy.
  • DNA is a huge molecule that holds the code for living things.
  • The smell of flowers comes from tiny molecules floating in the air.

Did You Know?

If you could line up the molecules in one spoonful of water, they would stretch much farther than to the Moon.