Even when liquids change their shape, they always take up the same amount of space. Their volume stays the same. Examples of gases include steam, helium and oxygen. They are often invisible.

Although the three states of matter are solid, liquid, and gas, not all substances seem to fit perfectly into one of these groups. Take a look at the substance below and see if you can decide whether ...

Understanding the three states of matter—solid, liquid, and gas—has long been guided by ... the molecular structure of the material—for example, water melts at 0 degrees Celsius, while ...

Gases, on the other hand ... they gain energy and can move more freely, changing from a solid to a liquid, for example. This basic model is, however, just that: there are many, many more states ...

Students explore the attractions and motion of atoms and molecules as they experiment with and observe the heating and cooling of a solid, liquid, and gas.

In gases the particles are far apart ... so would feel very heavy. Some liquids have a higher density than solids. For example, wood is a solid but has a lower density than water, which is ...