Figure 1 shows water being heated. Eventually the water changed into steam.

Complete the sentences. Choose answers from the box. Each answer may be used once, more than once or not at all.

Box: greater than, less than, the same as

1. The distance between the particles in steam is __________ the distance between the particles in liquid water.
2. The density of steam is __________ the density of liquid water.

When water (a liquid) is heated to its boiling point, it turns into steam (a gas). 1. In the liquid state, particles are close together but can move past each other. In the gaseous state, particles are much further apart and move randomly and quickly. Therefore, the distance between particles in steam is greater than in liquid water. 2. Density is mass per unit volume. Since the particles in steam are much more spread out, the same mass of water takes up a much larger volume as steam. A larger volume for the same mass means a lower density. Therefore, the density of steam is less than the density of liquid water.