Primary
Liquid ○｜Definition｜1st｜20260327112802-00-⌔
Liquid
Liquid is a state of matter with a definite volume but no fixed shape. When confined in a container and subjected to a force such as gravity, liquids will adapt to the internal shape of the container in the direction of the force.1 Liquids are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to that of a solid, and much higher than that of a gas. Liquids are a form of condensed matter alongside solids, and a form of fluid alongside gases.
A liquid is composed of atoms or molecules held together by intermolecular bonds of intermediate strength. These forces allow the particles to move around one another while remaining closely packed. In contrast, solids have particles that are tightly bound by strong intermolecular forces, limiting their movement to small vibrations in fixed positions. Gases, on the other hand, consist of widely spaced, freely moving particles with only weak intermolecular forces.
As temperature increases, the molecules in a liquid vibrate more intensely, causing the distances between them to increase. At the boiling point, the cohesive forces between the molecules are no longer sufficient to keep them together, and the liquid transitions into a gaseous state. Conversely, as temperature decreases, the distance between molecules shrinks. At the freezing point, the molecules typically arrange into a structured order in a process called crystallization, and the liquid transitions into a solid state.
Although liquid water is abundant on Earth, this state of matter is actually the least common in the known universe, because liquids require a relatively narrow temperature/pressure range to exist. Most known matter in the universe is either gaseous (as interstellar clouds) or plasma (as stars).
Printed 2026-06-28.
(echo:: @ ᯤ)
Link to original Footnotes
Liquid does not have this property in a low gravity environment, unless some other force or balance of forces of sufficient magnitude acts upon it, such as in an ullage motor. On the Earth’s surface under standard gravity, this property can also be disrupted by other forces such as surface tension, when the liquid suspended as an aerosol, or when it is in motion. ↩
Secondary
• • •