Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Physical Properties of Liquids

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The physical properties of a liquid describe how the liquid behaves under different temperatures and pressures and how it behaves when it comes into contact with other substances. Some liquids boil and evaporate at extremely low temperatures, while others boil at extremely high temperatures. For example, liquid helium boils at -269° C (-452° F), while liquid platinum boils at 3825° C (6917° F). Liquids also vary widely in freezing point and viscosity (a property that measures how a liquid flows). In addition, liquids behave differently when they come into contact with solids and when they mix with other liquids.

A. Boiling Point