A liquid is a state of matter in which a sample of matter

• flows and can change its shape.
• is not easily compressible and maintains a relatively fixed volume.

A sample of bromine (Br₂) at room temperature is shown below.

This bottle contains both liquid bromine [Br2(l), the darker phase at the bottom of the bottle] and gaseous bromine [Br2(g), the lighter phase above the liquid]. The circles show microscopic views of both liquid bromine and gaseous bromine.

As may be seen in the microscopic view of liquid bromine,

• Liquids are made up of very small particles (atoms, molecules, and/or ions).
• The particles that make up a liquid:
• are close together with no regular arrangement,
• vibrate, move about, and slide past each other.

The following figures show the microscopic behavior of the atoms in liquid argon and the molecules in liquid bromine and liquid water. Note how the molecules in a liquid move as units.

Microscopic view of the atoms in liquid argon.	Microscopic view of the Br2 molecules in liquid bromine.	Microscopic view of the H2O molecules in liquid water.