main question that people need to know the answer for a proper understanding of the picture of the world - that a substance in the chemistry.This concept is formed as early as school age child and send in further development.Getting to the study of chemistry, it is important to find common ground with it on an everyday level, it allows you to visualize and available to explain certain processes, definitions, properties, etc.
Unfortunately, due to imperfection of the education system, many are missing some fundamental basics.The concept of "substance in chemistry" - a kind of cornerstone timely absorption of this definition gives a person the right start in the subsequent development in the field of natural science.
Formation of concept
Before moving on to the notion of substance, it is necessary to determine what is the subject of chemistry.Substances - is that directly exploring the chemistry of their mutual transformations, structure and properties.In general, understanding the substance - this is what constitutes the physical body.
So, what is the substance in chemistry?By definition form the transition from the general concept of a purely chemical.The substance - a certain type of matter, always with a mass that can be measured.This characteristic distinguishes the agent from another type of matter - a field that has no weight (electric, magnetic, biological, etc.).Matter, in turn - is that of which we are created and all that surrounds us.
Several other characteristics of the matter, it is determined from what exactly it is - it is the subject of chemistry.The substances formed by atoms and molecules (some ions), which means any substance consisting of the formula units, and have substance.
Simple and complex matter
After mastering the basic definition can go to its complexity.The substances come in various levels of the organization, that is both simple and complex (or compound) - this is the first division into classes of materials, chemistry has a lot of subsequent separation, detailed and more complex.This classification, unlike many others, has a strictly defined borders, each connection can be clearly attributed to one of the species mutually exclusive.
simple substances in the chemistry - a compound composed of atoms of only one element of the periodic table.Typically, this binary molecule that is composed of two particles connected by a covalent non-polar connection - general education unshared electron pair.Thus, atoms of the same chemical element have identical electronegativity, i.e. the ability to hold the total electron density, so it is not displaced to any of the communication participants.Examples of simple substances (nonmetals) - hydrogen and oxygen, chlorine, iodine, fluorine, nitrogen, sulfur, etc.It consists of three atoms of a molecule of a substance such as ozone, and one - all noble gases (argon, xenon, helium, etc.).In metals (magnesium, calcium, copper, etc.), there is its own type of connection - metal, is carried out due to the socialization of the free electrons in the metal, and the formation of molecules as such is not observed.When the recording material of the metal indicated a chemical symbol without any indexes.
simple substances in chemistry, examples of which are described above, different from the qualitative composition of the complex.Chemicals atoms of different elements are formed from two or more.Such substances have the polar covalent or ionic type of binding.Since different atoms have different electronegativity, when the total electron pair formation occurs in its shift toward a more electronegative element, which leads to the total polarization of the molecule.Ion type - this is an extreme case of the Arctic, where a pair of electrons is completely transferred to one of the participants in the binding, then the atoms (or groups) are converted into ions.Clear boundaries between these types of no ionic bond can be interpreted as strongly polar covalent.Examples of complex compounds - water, sand, glass, salts, oxides, etc.
Modifications substances
substances called simple, actually have a unique feature that is not inherent in a complex.Some elements may form some form of simple substance.The basis of everything is just one element, but the quantitative composition, structure and properties of such radically different education.This feature is called allotropy.
oxygen, sulfur, carbon and other elements have several allotropic modifications.For oxygen - is O2 and O3, carbon makes four types of substances - carbine, diamond, graphite and fullerenes, molecules of sulfur is rhombic, monoclinic and plastic modifications.Such simple substance chemistry, examples of which are not limited to the above, is of great importance.In particular, fullerenes are used as semiconductors in technology, photoresists, additives for the growth of diamond films and for other purposes, and in medicine, is a powerful antioxidant.
What happens to the substance?
every moment in and around there is a transformation of substances.Chemistry examines and explains the processes that go with qualitative and / or quantitative changes in the composition of the reacting molecules.In parallel, often interconnected flow and physical transformation, which are characterized by a change in shape, color, materials, or the state of aggregation and other characteristics.
chemical phenomena - is the reaction of various kinds, for example, compounds of substitution, exchanging, expansion, reversible, exothermic oxidation-reduction, etc., depending on changes in the parameter of interest.The physical effects include: evaporation, condensation, sublimation, dissolution, freezing, electrical conductivity, etc.They often accompany each other, such as lightning during a thunderstorm - a physical process, and the selection under its ozone - a chemical.
physical properties
substance in chemistry - this matter, which are inherent in certain physical properties.In their presence, absence, extent and intensity you can predict how the substance behaves in different conditions, as well as explain some of the chemical properties of the compounds.For example, high boiling point organic compounds which have hydrogen and electronegative heteroatom (nitrogen, oxygen, etc.) indicate that the materials exhibit chemical type interactions such as hydrogen bonding.Thanks to the knowledge of what substances have the best ability to conduct electricity, cable and wire harness is made from certain metals.
chemical properties
established research and study of the properties of the other side of the coin is engaged in chemicals.The properties of materials from her point of view - this is their reaction interoperability.Some substances are very active in this respect, for example, metals or any oxidants and other noble (inert) gases under normal conditions in the reaction hardly enter.Chemical properties can activate or passivate when necessary, sometimes it is not particularly difficult, in some cases, have a hard time.Scientists spend many hours in laboratories, through trial and error achieving their goals, and sometimes do not reach them.By varying environmental parameters (temperature, pressure, etc.) or by using special compounds - catalysts or inhibitors - can affect the chemical properties of substances, and therefore the reaction.
Classification of the chemical
the basis of classification is the separation of compounds in the organic and inorganic.The main element of organic matter - is carbon bonded to each other and hydrogenic atoms of carbon to form hydrocarbon skeleton that after filling the other atoms (oxygen, nitrogen, phosphorus, sulfur, halogens, metals and others), closed in loops or branches, proving therebywide variety of organic compounds.Today, science knows 20 million of such substances.While mineral compounds only half.
Each compound individually, but also has many similar features to other properties, structure and composition, on this basis takes the grouping into classes of substances.Chemistry has a high level of systematization and organization, it is an exact science.
Inorganics
1. Oxides - binary compounds with oxygen:
a) acid - in contact with water produce acid;
b) the main - in contact with water give grounds.
2. Acid - a substance consisting of one or more protons and hydrogen acid residue.
3. Bases (alkalis) - made up of one or more hydroxyl groups and a metal atom:
a) amphoteric hydroxides - exhibit properties and acids and bases.
4. Salts - the result of the neutralization reaction between the acid and alkali (base soluble), consist of a metal atom and one or more acid residues:
a) acid addition salts - is an anion residue of an acid proton in the composition, the result of incomplete dissociation of the acid;
b) basic salts - is associated with the metal hydroxyl group, the result of incomplete dissociation of the base.
Organic compounds
class of substances in a great variety of organic matter, such a volume of information is difficult to immediately remember.The main thing is to know the basic separation of aliphatic and cyclic compounds, carbocyclic and heterocyclic, saturated and non.Also, hydrocarbons have many derivatives in which a substituted atom of Hydrogen on halogen, oxygen, nitrogen or other atoms, as well as functional groups.
substance in chemistry - is the foundation suschestovanie.Due to the organic synthesis of man today has a large number of artificial materials replacing natural and have no analogues in their characteristics in nature.
