ScholarIAm

Everything around us is made up of tiny particles called molecules. These molecules are always moving, but we can't see them because they're too small. When we add heat (thermal energy) to substances like water, something interesting happens to these invisible particles.

Think about what you observe when you heat water on a stove. At first, the water is calm and liquid. As it gets hotter, you might see small bubbles forming. Eventually, you see steam rising from the surface. This steam is actually water that has changed from a liquid to a gas!