solid
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What is a solid?
A solid is one of the three basic states of matter, distinct from liquid and gas. It maintains its shape when undisturbed. Solids form when the energy of atoms decreases, leading them to arrange into a relatively ordered, three-dimensional structure.
Solids have the ability to resist forces applied perpendicularly or parallel to a surface. They are divided into crystalline, noncrystalline (amorphous), and quasicrystalline types. Crystalline solids feature highly ordered, periodic arrangements of atoms, while amorphous solids lack a definite lattice pattern. Quasicrystalline solids display quasiperiodic arrangements.
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How are the particles arranged in a solid?
In solids, atoms are closely packed, exhibiting a definite shape and volume because their atoms or molecules are held in fixed positions. The atoms in a solid are not mobile. Each atom stays close to one point in space, although the atom is not stationary but instead oscillates rapidly about this fixed point.
There are three main types of arrangements in solids:
* Crystalline solids have a highly ordered, periodic arrangement of atoms, like metals and salts.
* Noncrystalline (amorphous) solids lack a definite lattice pattern. Atoms are not organized in a definite lattice pattern, like glass and plastic.
* Quasicrystalline solids display quasiperiodic arrangements, with patterns that don't repeat at regular intervals.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do solids differ from liquids and gases?
Solids, liquids, and gases are the three basic states of matter. A solid has a definite shape and volume, unlike liquids, which take the shape of their container while maintaining a constant volume, and gases, which expand to fill any available volume.
The atoms in solids are tightly packed and maintain a relatively ordered, three-dimensional structure, allowing them to resist forces. In contrast, liquids have atoms that are mobile, enabling them to move around, while gases have molecules that move almost independently of each other. These differences in atomic arrangement and mobility lead to the distinct macroscopic properties observed in solids, liquids, and gases.
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What are some common properties of solids?
Solids are a state of matter with distinct properties. They possess a definite shape and volume, and they resist forces whether applied perpendicularly or parallel to their surface.
On an atomic level, solids have a durable atomic-scale structure where atoms stay close to a fixed point in space, oscillating rapidly around it. These atoms are tightly bound, and can support substantial shearing force over time.
Solids are divided into crystalline, noncrystalline (amorphous), and quasicrystalline types. Crystalline solids have a high degree of order, while amorphous solids lack a definite lattice pattern. Quasicrystalline solids display symmetries in quasiperiodic fashion.
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What is the difference between crystalline and amorphous solids?
Crystalline solids have long-range order, where the position of each atom is precisely known throughout the crystal once the positions of an atom and its neighbors are known at one point. Most solid materials in nature are polycrystalline, composed of millions of grains (small crystals) packed together.
Amorphous solids, like glasses, lack long-range order but have short-range order. Rapid solidification from the molten state can make almost any material amorphous, though this state is unstable and will crystallize over time. The absence of long-range order is the defining characteristic of the atomic arrangement in amorphous solids.
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How do temperature and pressure affect the solid state of matter?
The effect of temperature and pressure on solids involves changes in volume and interatomic distances. Solids are one of the three basic states of matter with a definite shape and volume because their atoms or molecules are tightly packed and maintain a relatively ordered, three-dimensional structure.
Pressure and temperature can induce continuous or discontinuous changes in a solid's properties. High pressure reduces volume and shortens interatomic distances, leading to changes in physical properties, while increasing temperature can cause a solid to melt. Also, under sufficient pressure, every material undergoes structural transformations to denser atomic arrangements.
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solid, one of the three basic states of matter, the others being liquid and gas. (Sometimes plasmas, or ionized gases, are considered a fourth state of matter.) A solid forms from liquid or gas because the energy of atoms decreases when the atoms take up a relatively ordered, three-dimensional structure.
Solids exhibit certain characteristics that distinguish them from liquids and gases. All solids have, for example, the ability to resist forces applied either perpendicular or parallel to a surface (i.e., normal or shear loads, respectively). Such properties depend on the properties of the atoms that form the solid, on the way those atoms are arranged, and on the forces between them.
Solids are generally divided into three broad classes—crystalline, noncrystalline (amorphous), and quasicrystalline. Crystalline solids have a very high degree of order in a periodic atomic arrangement. Practically all metals and many other minerals, such as common table salt (sodium chloride), belong to this class. Noncrystalline solids are those in which atoms and molecules are not organized in a definite lattice pattern. They include glasses, plastics, and gels. Quasicrystalline solids display novel symmetries in which the atoms are arranged in quasiperiodic fashion—i.e., in patterns that do not repeat at regular intervals. They exhibit symmetries, such as fivefold symmetry, that are forbidden in ordinary crystals. Quasicrystal structures are common in alloys in which aluminum is combined with another metal, such as iron, cobalt, or nickel.
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Some molecules may exist in the liquid crystal state, which is intermediate to the crystalline solid and liquid states. Liquid crystals flow like liquids yet display a certain degree of the symmetry characteristic of crystalline solids.
Four principal types of atomic bonds are found in crystalline solids: metallic, ionic, covalent, and molecular. Metals and their alloys are characterized in the main by their high electrical and thermal conductivity, which arise from the migration of free electrons; free electrons also influence how the atoms bond. Ionic crystals are aggregates of charged ions. These salts commonly exhibit ionic conductivity, which increases with temperature. Covalent crystals are hard, frequently brittle materials such as diamond, silicon, and silicon carbide. In the simpler, monatomic types (e.g., diamond), each atom is surrounded by a number of atoms equal to its valence. Molecular crystals are substances that have relatively weak intermolecular binding, such as dry ice (solidified carbon dioxide), solid forms of the noble gases (e.g., argon, krypton, and xenon), and crystals of numerous organic compounds.
Various alloys, salts, covalent crystals, and molecular crystals that are good electrical insulators at low temperature become conductors at elevated temperatures, conductivity increasing rapidly with temperature. Materials of this type are called semiconductors. Their electrical conductivity is generally low when compared with that of such metals as copper, silver, or aluminum.