Today we know of the existence of more than 3 million different substances.And this figure is increasing every year, as synthetic chemists and other scientists are constantly made experiments to obtain new compounds having any useful properties.
Some substances - are natural inhabitants, naturally formed.The other half - artificial and synthetic.However, in the first and in the second case, make up a significant portion of gaseous substances, examples and characteristics that we look at in this article.
physical state of matter
In the XVII century it was customary to assume that all the known compounds can exist in three states: solid, liquid, gaseous.However, detailed studies of the last decades in the field of astronomy, physics, chemistry, space biology and other sciences have proven that there is another form.This plasma.
What is it?It is partially or fully ionized gases.And it turns out these substances in the universe is the vast majority.So, it is in the plasma state are:
- interstellar matter;
- cosmic matter;
- higher layers of the atmosphere;
- of many of the planets;
therefore say today that there are solid, liquid, gaseous and plasma.By the way, each gas can be artificially transformed into such a state, if the subject of ionization, that is, to make turn into ions.
gaseous substance: examples
Examples of the substances can cause a lot.After the gases have been known since the XVII century, when van Helmont, naturalist, first received the carbon dioxide and began to explore its properties.By the way, the name of this group of compounds also gave it, because, in his opinion, gases - it is something disordered, chaotic associated with spirits and something invisible but palpable.This name stuck and in Russia.
can classify all the gaseous substances, examples lead time will be easier.It is difficult to cover all the diversity.
The composition of distinction:
- complex molecules.
The first group are those that are composed of identical atoms in any quantity.Example: oxygen - O2, ozone - O3 hydrogen - H2 chloro - CL2, F - F2, nitrogen - N2, and others.
second category should be classified as such compounds, which include a few atoms.This will be challenging gaseous substances.Examples are:
- hydrogen sulfide - H2S;
- chloride - HCL;
- methane - CH4;
- sulfur dioxide - SO2;
- brown gas - NO2;
- freon - CF2CL2;
- Ammonia - NH3 and others.
classification of naturally occurring substances
also can be classified by types of gaseous substances belonging to the organic and inorganic world.That is, by the nature of the incoming atoms.Organic gases are:
- first five representatives of saturated hydrocarbons (methane, ethane, propane, butane, pentane).The general formula CnH2n + 2;
- ethylene - C2H4;
- acetylene or ethyne - C2H2;
- methylamine - CH3NH2 and others.
The category gas inorganic nature are chlorine, fluorine, ammonia, carbon monoxide, silane, laughing gas, inert or noble gases, and others.
Another classification, which can be subjected to the subject compounds is based on the division of the members of the particles.It does not consist of atoms of all the gaseous substances.Examples of structures in which there are ions, molecules, photons, electrons, Brownian particles plasma also belong to the compounds in such a state of aggregation.
Features substances in this state differ from those for solid or liquid compounds.The fact is that the special properties of gaseous substances.The particles are easily and quickly movable, generally isotropic material, i.e. the properties are not determined by the direction of motion included in the structures.
can designate the most important physical properties of gases, which will distinguish it from all other forms of existence of matter.
- These are compounds that can not be seen and monitored, to feel ordinary human ways.To understand the properties and identify one or another gas, based on four parameters describing them all pressure, temperature, amount of substance (mole) amount.
- Unlike liquid gases are able to occupy space without reserve, limited only by the size of the vessel or a room.
- All gases mix easily with each other, wherein these compounds have the interface.There
- lighter and heavier representatives so under the action of gravity and time may see their separation.
- Diffusion - one of the most important properties of these compounds.The ability to penetrate into other substances and nourish it from the inside, making it absolutely disorderly movements within its structure.
- Real gases conduct electricity may not, but if we talk about the rarefied and ionized substances, the conductivity increases dramatically.
- heat and thermal conductivity of gases is low and varies in different species.
- viscosity increases with pressure and temperature.
- There are two variants of interphase transition: evaporation - liquid turns into steam, sublimation - solid, bypassing the liquid becomes gaseous.
distinctive feature of the true vapor gases that first under certain conditions can go into a liquid or solid phase, and the second is not.It should also be noted the ability of the subject compounds to resist deformation and to be fluid.
Similar properties of gaseous substances allow their widespread use in various fields of science and technology, industry and the national economy.In addition, the specific characteristics of each representative are strictly individual.We have considered only common to all features of real structures.
at different temperatures and under the influence of pressure gases can be compressed, increasing your concentration and reducing the occupied space.At elevated temperatures, they are expanding, at low - compressed.
Under pressure as changes occur.The density of gases increases, and when it reaches a critical point, which each has its own representative, may come a transition to another state of aggregation.
basic scientists who have made contributions to the development of the doctrine of gases
Such people can be called a lot, because the study of gas - a laborious process, and historical debts.Let us dwell on the most famous people who were able to make the most significant discoveries.
- Amedeo Avogadro in 1811 made the discovery.Any what gases, most importantly, that under identical conditions in one of them contained an equal volume amount by the number of molecules.There is a calculated value that has the name of the scientist by the name.It is equal to 6.03 * 1023 molecules to 1 mole of any gas.
- Fermi - he created the doctrine of the ideal quantum gas.
- Gay-Lussac, Boyle - the names of the scientists who created the master equation for the calculations.
- Robert Boyle.
- John Dalton.
- Jacques Charles and many other scientists.
The main feature in the construction of the crystal lattice of the substances in question, is that the nodes it either atoms or molecules that are connected to each other by weak covalent bonds.Also present strength of the van der Waals interaction, in the case of ions, electrons and other quantum systems.
Therefore, the main types of structure arrays for gases is:
communication within easily torn, however, these compounds do not have a constant shape and fill the entire spatial volume.It also explains the absence of electrical conductivity and poor thermal conductivity.But good insulation from the gas, because, thanks to diffusion, they are able to penetrate the solid body and occupy the free space within their cluster.The air is not passed, the heat is retained.This is based on the use of gases and solids in the aggregate for construction purposes.
simple matter of the gases
What in the structure and composition of gases belong to this category, we have already indicated above.Are those that are made up of the same atoms.Examples are many, because a significant portion of non-metals from the entire periodic system under normal conditions, there is in this state of aggregation.For example:
- white phosphorus - one of the allotropic forms of this element;
molecules of these gases may be both mono- (noble gases), and polyhydric (ozone - O3).Type of connection - covalent nonpolar, in most cases rather weak, but not all.Crystalline molecular type, which allows these substances to pass easily from one state to another.Thus, for example, iodine under normal conditions - Dark violet crystals with metallic luster.However, when heated to sublimate clubs bright purple gas - I2.
By the way, any material, including metals, under certain conditions can exist in a gaseous state.
complex nature of the gaseous compound
such gases, of course, the majority.Different combinations of atoms in molecules, combined with covalent bonds and van der Waals interactions, allows you to create hundreds of different representatives considered the state of aggregation.Examples
is complex substances of the gases may be all compounds consisting of two or more different elements.These include:
- carbon disulfide;
- sulfur dioxide;
- brown gas;
- ethylene and others.
Crystalline molecular type.Many representatives readily dissolve in water, forming the corresponding acid.Most of these compounds - important part of chemical syntheses conducted in the industry.
methane and its homologs
Sometimes the general concept of "gas" means natural minerals, which is a whole mixture of gaseous products mostly organic nature.That is, it contains substances such as:
- pentane and others.
In the industry, they are very important, because it is a mixture of propane-butane - is natural gas, where people prepare food, which is used as a source of energy and heat.
Many of them are used for the synthesis of alcohols, aldehydes, acids and other organic substances.Annual consumption of natural gas trillions of cubic meters, and rightly so.
oxygen and carbon dioxide
What gaseous substances can be called the most widespread and well-known even to first-graders?The answer is obvious - oxygen and carbon dioxide.After this they are directly involved in gas exchange that occurs in all living beings on the planet.
known that it is due to oxygen can be life, because without it, can only exist some types of anaerobic bacteria.A carbon dioxide - a necessary product of "food" for all plants that absorb it to implement the process of photosynthesis.
From the chemical point of view, and oxygen and carbon dioxide - the important substances for the syntheses of the compounds.The first is a strong oxidant, the second most reductant.
It's a group of compounds in which the atoms - a gaseous substance particles are connected in pairs to each other by a non-polar covalent bond.However, not all the halogens - gases.Bromine - is a liquid under normal conditions, and iodine - easily sublimated solid.Fluorine and chlorine - poisonous dangerous to the health of living beings substances which are strong oxidizing agents and are used in the synthesis of very wide.