•When you open a bottle with a smell inside, it soon spreads into other areas of the room.

•That is because the smell spreads through the air in all different directions.

•When the lid is on, the gas particles remain inside the bottle.

•When the lid is taken off, the liquid smell evaporates easily.

•Since there are only weak forces between the particles, they can spread out, moving away from the crowded bottle.

• The particles then go to places where there are fewer particles of liquid smell.

• Eventually the particles spread evenly throughout the room the air in.

When the lid is on the particles remain inside the container.

When the lid is being taken off, some of the particles immediately escape.

When the lid is completely removed, most of the particles rise out of the container.