Structure of Liquids
. Liquids, like all substances, are made up of atoms or bonded groups of atoms called molecules . The physical state of any substance—whether the substance is a liquid, solid , or gas —depends on the arrangement of the molecules in the substance. The molecules in a liquid are arranged tighter and more orderly than in a gas, but less orderly than in a solid. In crystalline solids, such as table salt or sugar, the molecules or other particles are stacked in a precise order, forming a three-dimensional pattern that repeats throughout the crystal . Scientists say these substances have long-range order. This means the atoms or molecules in the solid are ordered throughout the solid. In gases, the atoms or molecules have no order at all but move freely, allowing gases to expand and fill a container. Liquids have no long-range order, but their molecules have some order with respect to the nearest neighboring molecules. Every molecule in a liquid has the same number of nearest neighbors, and