in physics and chemistry marks the term solid body subject in the firm state of aggregation. This is a special case of the condensed subject. Strictly speaking one understands by this also a material, which at a temperature of 20 °C a firmState of aggregation exhibits, whereby the designation is solid in this case material-specifically, however not temperature specific.
The physics and chemistry of the solids differ due to the mutual reciprocal effect of the components of the subject substantially the physics and chemistry of free particles or inSolution. Special characteristic of solids is the stability of the order (amorphous or crystalline) of their components.
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structure of solids
solids having in the technical linguistic usage a certain minimum expansion, which is however not sharply defined. They are therefore macroscopic bodies - contrary to microscopic bodies. For example appliesin the rule a macromolecule for itself alone not yet as solids.
All solids can one from components compound introduce oneself. Ein Baustein kann dabei ein einzelnes Atomoder Molekül, aber auch eine Gruppe davon sein. If all components are homogeneous, soone speaks of mono structures, otherwise of heterostructures.
one differentiates between amorphous (in the smallest “formless”) and crystalline solids. Solid-state physics predominantly concerns itself with the characteristics of crystalline solids. Among them becomes - as in geology -fine structure understood, how it is recognizable for example with the marble from sparkling smallest grains. The word crystalline means quasi miniature of crystals.
Contrary to rocks however this structure is with most in solid body or geophysics, industry and Technology regarded or used solids many more finely and even in the microscope when strong enlargement hardly recognizably. An exception of it are for example the Weiss districts of metals, which are responsible for the ferromagnetism.
- Single crystals
- characteristic characteristic of crystals is thoseregular arrangement of their components. The kind of the underlying structure is responsible for many characteristics of a solid body. For example carbon possesses two different crystal structures -- Graphite and diamond -- which have completely different electrical conductivenesses (graphite leads the river, diamond is in Insulator).
- Amorphous solids
- the physics of the amorphous solids is multilayered, because by this all solids are summarized, which do not possess regular structure. Water ice, glasses or rigid liquids are only some representatives of this kind. With the loss of a macroscopic structureare lost also many typical characteristics of a crystal. For example most amorphous solids are bad electrical conductor. This area nevertheless represents an interesting topic in the research, there an absence of the crystal structure also an absence of anisotropy - effects means.
- Polycrystallines solid body
- crystalline and amorphously are not the only-possible manifestations of solids. Between them there is a range, which represents to a certain extent a combination: Polycrystallines the solids. These consist of an accumulation of small single crystals, which blocks unordered to a large whole one are.
to connections the co-operation of a solid body on attractive reciprocal effects between the atoms and/or. Molecules on large distances and a repulsiven on short. One calls the energetically most favorable distance equilibrium distance. The thermal energy is thatTo escape atoms too low around these Potenzialfalle, then arrangements out the atoms form rigid are together bound.
There are essentially four kinds of connection, which affect the structure and the characteristics of a solid body considerably.
- this kindarises to the connection - at least proportionately - always, if the solid body from unterschliedlichen elements is developed, which possess a different Elektronegativität. Element the other one delivers an electron, thus one to the anion and the other onethe cation becomes. The different charges cause an electrostatic attraction. Salts are a typical representative of this kind of connection.
- Atomic bond
- this, also kovalent mentioned, connection been based on lowering the electronic energy. The principle the same as with the education ofMolecules like e.g.O 2. Elements of the fourth main group (carbon, silicon, germanium) are bound in this kind. One calls the condition of the electrons then also FR 3 - hybridizing .
- Metallic binding
- the metallic binding is an extreme case of the atomic bond. Also this connection is due to a sinking of the electronic energy. Only it is overlaps here the orbital of the atoms so largely that these interact to its (or still more) neighbour after the next also still with those. Oneit can imagine in such a way that the ion cores of the atoms are embedded in sea of electrons. Like the name already suggest, metals train this connection.
- Van that Waals connection
- the Van that Waals connection arises itself in principle always, is however so weakly, it onlywith absence of another kind of connection makes noticeable. Attractive Kraft is an electrostatic, however by induced dipole moments is caused here. Noble gas and molecule crystals are held together only by these.
These kinds of connection are not by any means isolated cases, which only arise either or. The transitionfrom more ionischer to more kovalenter to metallic connection is flowing. Besides different connections can occur next to each other in solids. Graphite e.g. consists of layers kovalent bound carbon atoms, while the layers hold together as a whole among themselves over Van that Waals connections. There latter connection so weaklyis, one uses graphite as pencil mines - when rubbing over paper the connections already tear up.
with the surface one means the locking 1-3 atomic situations at the border to the vacuum. The absence from connection partners to oneSide draws a überlichlicherweise relaxation or recombination for atoms of these layers . The atoms try to take an energetically more favorable condition by changing their connection length to more deep-seated layers (relaxation) or by rearranging their positions and saturating open connections (recombination).The result are new surface textures, which can exhibit another periodicity than the substrate (more deep-seated layers).
A further characteristic is the occurrence of surface qualities. That means that in for energetic ranges otherwise forbidden -- the gaps-- permittedEnergy conditions for electrons to develop can. With semiconductors these new conditions ensure for a buckling of the volumes and thus a change of the electrical conductivity. Raceways can develop in such a way, which is used for example for field-effect transistors.
conductivity all solids after their ability to be led to the leaders, semiconductors or nonconductors be assigned electric current. This organization was specified historically in such a way. An explanation for the differences of the conductivity could do however only that Band model supply. Nowadays therefore the group allocation is specified by the size of the gap.
- nearly all metals rank among the electrically good leaders. The conduction electrons behave in such a way, as if they can move freely in the solid body. At rising temperaturethe conductivity decreases however, which can be justified with increased impacts of the electrons among themselves and at defects in the crystal structure.
- most remarkable characteristic of the conductivity of semiconductors is their strong dependence on internal (degree of purity) like also outside parameters (Temperature). With pure (intrinsische) semiconductors the conductivity increases at rising temperature very strongly -- often around an order of magnitude with approx. 20 K difference. Beside electrons here also so-called mobile holes , also mentioned, contribute holes to the conductivity. Those Charge carrier densities of holes and electrons are in intrisischen semiconductors equally large, which knows relationship however by purposeful contaminating (to endow) is on one side changed.
- insulators lead no electric current under normal circumstances practically.
The electrical conductivity belongs to thatmost variable sizes in physics, the possible values extend over more than 30 orders of magnitude. Most non-magnetic solids show at very low temperatures a further amazing effect: Below a critical temperature the electrical resistance disappears completely, this conditionone calls superconducting phase.
different than with liquids and gases the particles are only minimum mutually adjustable in the firm state of aggregation - according to their crystal-like fine structure. In the smallest such deformations are only with difficulty modelable, but overMillions or quintillions of particles follow them clear laws. They are connected with the elasticity and their modules , as well as with the form and dimension of the bodies which can be distorted.
An idealized solid body, that in the classical mechanics as model oneSolid body is used, is the rigid body. It is not subject to any deformations, does not occur however in nature. It is in most cases a good model for the material objects in our environment. The material solid body however hasusually no simple, but a direction-controlled ductility. This treats for example the solid-state physics and the theory of subject waves.
solid reactions are characterised reactivity compared with reactions in solution normally by very high activation barriers.The reason is the reaction mechanism, after which solid reactions run off: The blank characters in the crystal lattice move as in a “sliding puzzle”. But the crystal structure must be distorted, which causes a large energy expenditure.