Solid referred to those substances which are capable of forming the body and have a volume.From liquids and gases, they are distinguished by their shape.The solids retain the shape of the body due to the fact that their particles are capable of moving freely.They differ in their densities, plasticity, electrical conductivity and color.They also have other properties.For example, most of these substances are melted during heating, acquiring the liquid aggregate state.Some of them in the heating immediately transformed into gas (sublime).But there are also those which decompose to other substances.
Types solids
All solids were divided into two groups.
- amorphous, in which the individual particles are chaotic.In other words, they do not clear (determined) structure.The solids are able to melt in a certain prescribed temperature interval.The most common of these include glass and resin.
- Crystal, which in turn are divided into 4 types: atomic, molecular, ionic, metallic.The particles are located only in a specific pattern, namely the lattice points.Its geometry in different substances can vary greatly.
crystalline solid amorphous prevail over in numbers.
types of crystalline solids
In almost all solid substances have a crystalline structure.They differ in their structure.In their crystalline lattice sites contain various particles and chemicals.It is in accordance with them, and they got their names.Each type has a characteristic property:
- In atomic crystal lattice of the solid particles are linked by a covalent bond.It is distinguished for its durability.Due to this, such substances have a high melting point and boiling point.This type includes quartz and diamond.
- In molecular lattice bond between the particles is characterized by its weakness.Substances of this type are characterized by ease of boiling and melting.They differ volatility through which have a certain smell.Such solids include ice sugar.Movement of molecules in solids of this type are characterized by their activity.
- The ionic crystal lattice sites alternate corresponding particles, charged positively and negatively.They are held by electrostatic attraction.This type of grating exists in alkalis, salts, basic oxides.Many substances of this kind are water-soluble.Due to quite a strong bond between the ions are refractory.Almost all of them have no smell, because they are characterized by non-volatility.Substances with ionic lattice are unable to conduct electricity, because their composition no free electrons.A typical example of an ionic solid - salt.Such a crystal lattice gives it brittle.This is due to the fact that each of its offset can cause repulsive forces ions.
- The metallic crystal lattice sites are present only ions chemicals positively charged.Between them there are free electrons through which a great pass thermal and electrical energy.That is why any different metals such feature as conductivity.
General concepts of solid
solids and substances - it is almost the same.These terms referred to one of the four states of aggregation.Solids have a stable shape and character of the thermal motion of the atoms.The latter make small oscillations near the equilibrium positions.Section of science that studies the composition and internal structure, called a solid-state physics.There are other important areas of knowledge involved in such substances.The change in shape under external actions and movement called solid mechanics.
Due to different properties of solids, they have been used in various technical devices, created by man.Most often lie on their use properties such as hardness, volume, mass, elasticity, plasticity and brittleness.Modern science can be used, and other quality of solids which can be detected only in the laboratory.
What crystals
crystals - a solid body arranged in a certain order particles.Each chemical has its own structure.Its atoms form a three-dimensional periodic stacking called lattice.The solids have different symmetry structure.The crystalline state of the solid is considered resistant, because it has a minimum amount of potential energy.
vast majority of solid materials (natural) consists of a large number of randomly oriented individual grains (crystallites).Such substances are called polycrystalline.These include technical alloys and metals, as well as a lot of rocks.Monocrystalline called single natural or synthetic crystals.
Most of these solids are formed out of the liquid phase, represented by melt or solution.Sometimes, they are derived from a gaseous state.This process is known as crystallization.Thanks to scientific and technical progress of cultivation procedure (synthesis) of various substances obtained commercially.Most of the crystals has a natural shape in the form of regular polyhedra.Their sizes vary widely.So, natural quartz (rock crystal) can weigh up to hundreds of kilograms, and diamonds - up to several grams.
In amorphous solids, atoms are in constant fluctuation around randomly located points.They saved some short-range order, but no long-range.This is because their molecules are arranged at a distance which can be compared with their size.The most common in our life example of such a solid glassy state.Amorphous materials are often treated as an infinite liquid with viscosity.Time crystallization is sometimes so great, that does not manifest itself.It
above properties of these substances make them unique.Amorphous solids are considered to be unstable, as time may go to the crystalline state.
molecules and atoms that make up solid, packed with high density.They practically retain their relative position with respect to other particles and are held together by intermolecular interactions.The distance between the molecules of a solid in various areas of the crystal lattice parameter name.The structure of matter and its symmetry define a number of properties, such as e-zone, cleavage and optics.When exposed to solid sufficiently large force, these qualities may be more or less violated.In this solid gives in permanent deformation.
atoms solids oscillate, which is due to possession of thermal energy.Since they are negligible, they can be observed only under laboratory conditions.The molecular structure of solid greatly affects its properties.
study of solids
Features, properties of these materials, their quality and movement of particles are studied by various subsections of Solid State Physics.
used for the study: radio spectroscopy, structural analysis using X-rays and other methods.So study the mechanical, physical and thermal properties of solids.Hardness, resistance to stress, tensile strength, phase transformations studying materials science.It largely overlaps with the physics of solids.There is another important modern science.A study of existing and synthesizing new substances held solid state chemistry.
Features solids
nature of the motion of the outer electrons of atoms solid determines many of its properties, such as electrical.There are 5 classes of such bodies.They are set according to the type of atoms:
- Ion, whose main characteristic is the force of electrostatic attraction.Its features: reflection and absorption of light in the infrared region.At low temperature ionic bond is characterized by low conductivity.An example of such a substance is a sodium salt of hydrochloric acid (NaCl).
- Covalent carried out by an electron pair, which belongs to both atoms.Such communication is divided into: single (simple), double and triple.These names indicate the presence of pairs of electrons (1, 2, 3).Double and triple bonds are called multiples.There is another division of the group.So, depending on the electron density distribution is isolated polar and nonpolar bond.The first is formed by different atoms, and the second - the same.Such solid state, examples of which are - a diamond (C) and silicon (Si), characterized by its density.Most solid crystals relate specifically to the covalent bond.
- metal formed by combining the valence electrons of atoms.As a result, there is a total electron cloud, which moves under the influence of an electric voltage.The metal bond is formed when the bonding atoms long.That they are able to donate electrons.Many metals and complex compounds of the bond formed solid state of matter.Examples: sodium, barium, aluminum, copper, gold.Because of non-metallic compounds are the following: AlCr2, Ca2Cu, Cu5Zn8.Substances with a metal bonding (metals) are diverse in physical properties.They may be liquid (Hg), mild (Na, K), very hard (W, Nb).
- Molecular occurring in the crystals, which are formed by individual molecules of the substance.It is characterized interstices between molecules with zero electron density.The forces that bind the atoms in such crystals are considerable.At the same molecules are attracted to each other only weak intermolecular attraction.That is why the connection between them is easily destroyed by heating.The connections between the atoms collapse much more difficult.The molecular bond is divided into orientation, dispersion and induction.An example of such a substance is a solid methane.
- hydrogen that occurs between the positively polarized atoms of the molecule or part thereof and negatively polarized smallest particle of a molecule or the other part.These relations can be attributed ice.
properties of solids
What do we know today?Scientists have been studying the properties of the solid state of matter.When exposed to temperature changes, and it is.The transition of the body fluid called melting.The transformation of solid to the gaseous state is called sublimation.By lowering the temperature of crystallization of the solid.Some substances under the influence of the cold transferred to the amorphous phase.This process is called vitrification scientists.
In phase transitions change the internal structure of solids.The largest order it acquires the temperature is lowered.At atmospheric pressure and a temperature T & gt;0 By any substance existing in nature, solidify.Only helium, which is necessary for the crystallization pressure of 24 atm, is an exception to this rule.
solid state gives it a different physical properties.They describe the specific behavior of bodies under the influence of certain fields and forces.These properties are divided into groups.There are 3 ways to impact, the corresponding 3 kinds of energy (mechanical, thermal, electromagnetic).Accordingly, there are 3 groups of them physical properties of solids:
- mechanical properties associated with the stress and strain of bodies.These criteria are divided into solids elastic, rheological, strength and technology.At rest a body retains its shape, but it can vary under the influence of an external force.At the same time it can be plastic deformation (initial appearance will not be returned), elastic (returns to the original shape) or destructive (when a certain threshold decays / fault).Review these efforts describe elastic moduli.Solid not only resists compression, tension, but also shifts, torsion and bending.The strength of a solid body is called his property to resist destruction.
- Thermal manifested under the influence of thermal fields.One of the most important properties - the melting temperature at which the body passes into a liquid state.It is observed in crystalline solids.Amorphous substances have a latent heat of fusion, as they transition to the liquid state when the temperature rises gradually.Upon reaching a certain heat amorphous body loses its elasticity and becomes plasticity.This state means achieving their glass transition temperature.When heated, the deformation of the solid body.Moreover, it often expands.Quantitatively, this condition is characterized by a certain factor.Body temperature affects the mechanical properties such as fluidity, flexibility, hardness and durability.
- Electromagnetic associated with exposure to solid microparticles and flow of electromagnetic waves of high rigidity.These include probation and radiative properties.
band structure
solids classified and the so-called band structure.For example, among them distinguish:
- conductors, characterized in that the zone of conduction and valence bands overlap.Thus the electrons can move between them, yielding the smallest energy.For conductors are all metals.When applying for such a body to a potential difference generated electricity (thanks to the free movement of electrons between the points with the lowest and high potential).
- dielectrics areas that do not overlap.The interval between them is more than 4 eV.To carry electrons from the valence zone to the ongoing need more energy.Due to such properties dielectrics virtually non-conductive.
- Semiconductors, characterized by the absence of the conduction and valence.The interval between them is smaller than 4 eV.To transfer electrons from the valence zone to the ongoing need less energy than dielectrics.Pure (unalloyed and own) semiconductors bad current is passed.
movement of molecules in solids, determine their electromagnetic properties.
Other properties
Solids are divided and its magnetic properties.There are three groups:
- diamagnetic materials whose properties depend little on the temperature or the state of aggregation.
- paramagnetic resulting orientation of conduction electrons and magnetic moments of the atoms.According to Curie, their sensitivity decreases in proportion to temperature.Thus, at 300 K, it is 10-5.
- body ordered magnetic structures with long-range order of atoms.In the nodes of the lattice are periodically arranged particles with magnetic moments.These solids and substances frequently used in different spheres of human activity.
hardest substance in nature
What are they?The density of solids largely determine their hardness.In recent years, scientists have discovered several materials that claim to be "the most durable body."Most solid - this Fuller (crystal molecules of the fullerene), which is about 1.5 times harder than diamond.Unfortunately, it is currently only available in extremely small quantities.
Today most solid which subsequently may be used in the industry - lonsdalite (hexagonal diamond).It is 58% harder than diamond.Lonsdale - allotropic modification of carbon.Its crystal lattice is very similar to diamond.Lonsdaleite cell contains 4 atoms, and a diamond - 8. From crystals widely used today is the hardest diamond.
