A liquid will not expand to fill a container like a gas, but will take the shape of the container to the extent that the liquid fills the container. The shape of liquids is not rigid, but liquids have a definite volume. Liquids flow so we can deduce that the atoms or molecules in the liquid can move around each other. The volume of a liquid will change only slightly with temperature and liquids are incompressible.

Liquids can be pure substances or mixtures. Most liquids are mixtures. There are two known elements which exist as liquids and there are a number of compounds that exist as liquids. The most common liquid is water. Most liquids are not pure substances, but mixtures of many different components.

How do we represent a liquid at the microscopic level?

In our representation the atoms are located in the bottom of the container, they do not fill the container as like a gas, because a liquid is a condensed state. The atoms are not ordered like they are in a solid, since liquids can flow. So the representation of a liquids has the atoms or molecules more disordered, than ordered.