Organic Chemistry-Hydro Carbon

Hydro carbon

Any of a class of organic compounds composed only of carbon and hydrogen.

The carbon atoms form the framework, and the hydrogen atoms attach to them.

Hydrocarbons, the principal constituents of petroleum and natural gas, serve as fuels, lubricants, and raw materials for production of plastics, fibres, rubbers, solvents, explosives, and industrial chemicals.

All burn to carbon dioxide and water with enough oxygen or to carbon monoxide without it.

The two major categories are aliphatic, with the carbon atoms in straight or branched chains or in nonaromatic rings, and aromatic (see aromatic compound).

Aliphatic compounds may be saturated (paraffins) or, if any carbon atoms are joined by double or triple bonds, unsaturated (e.g., olefins, alkenes, alkynes). All but the simplest hydrocarbons have isomers (see isomerism). Ethylene, methane, acetylene, benzene, toluene, and naphthalene are hydrocarbons.

Oranic Chemistry-Carbon

Carbon

• Nonmetallic chemical element, chemical symbol C, atomic number 6.

• The usual stable isotope is carbon-12; carbon-13, another stable isotope, makes up 1% of natural carbon.
• Carbon-14 is the most stable and best known of five radioactive isotopes (see radioactivity);
• its half-life of approximately 5,730 years makes it useful in carbon-14 dating and radiolabeling of research compounds.
• Carbon occurs in four known allotropes: Diamond, graphite, carbon black (amorphous carbon including coal, coke, and charcoal), and hollow cage molecules called fullerenes.
•  Carbon forms more compounds than all other elements combined; several million carbon compounds are known.
• Each carbon atom forms four bonds (four single bonds, two single and one double bond, two double bonds, or one single and one triple bond) with up to four other atoms.
•  Multitudes of chain, branched, ring, and three-dimensional structures can occur.
• The study of these carbon compounds and their properties and reactions is organic chemistry (see organic compound). With hydrogen, oxygen, nitrogen, and a few other elements whose small amounts belie their important roles, carbon forms the compounds that make up all living things: proteins, carbohydrates, lipids, and nucleic acids.
• Biochemistry is the study of how those compounds are synthesized and broken down and how they associate with each other in living organisms.
•  Organisms consume carbon and return it to the environment in the carbon cycle. Carbon dioxide, produced when carbon is burned and from biological processes, makes up about 0.03% of the air, and carbon occurs in Earth's crust as carbonate rocks and the hydrocarbons in coal, petroleum, and natural gas. The oceans contain large amounts of dissolved carbon dioxide and carbonates.                                                                         

• Half Life

Interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or the time required for the number of disintegrations per second of a radioactive material to decrease by one-half.

Half-lives are characteristic properties of the various unstable atomic nuclei and the particular way in which they decay. Alpha decay and beta decay are generally slower processes than gamma decay.

Vandar Waals Forces

VANDER WAALS FORCES

Relatively weak electrical forces that attract neutral (uncharged) molecules to each other in gases, liquefied and solidified gases, and almost all organic liquids and solids.

Solids held together by van der Waals forces typically have lower melting points and are softer than those held together by ionic, covalent, or metallic bonds (see bonding). The forces arise because neutral molecules, though uncharged, are usually electric dipoles, which have a tendency to align with each other and to induce further polarization in neighbouring molecules, resulting in a net attractive force. They are somewhat weaker than the forces involved in hydrogen bonding. See also Johannes D. van der Waals

Vinegar

Vinegar

Sour liquid obtained by fermentation of dilute alcoholic liquids.

Probably first made from wine (French vinaigre means “sour wine”), vinegar may also be made from malted barley, rice, cider, or other substances. The source substance, which must contain sugar, is fermented by yeast to produce alcohol. The alcohol is then aerated, which causes it to convert, through the action of Acetobacter bacteria, to acetic acid, water, and various other compounds. Vinegar is used in pickling meat, fish, fruits, and vegetables and in creating marinades, dressings, and other sauces.

Wine

WINE

Red Wine

Wine may also be made from various fruits and plant parts. Though known by the ancients, wine was not drunk in its matured form until the development of the bottle and cork in the late 17th century. In wine manufacture, grapes are crushed and strained, and the juice (called must) is sealed in vats along with yeast (Saccharomyees ellipsoideus) and often sulfur dioxide, which suppresses wild yeasts and organisms. Fermentation continues for several weeks, and then the wine is drawn off (“racked”) into wooden barrels or other containers for a second fermentation (“aging”). It is clarified and bottled before undergoing final maturation. Wines may be classified according to colour as red, rosé (pink), or white; colour depends on whether the skins of red grapes are allowed to ferment with the juice. Wine taste is described as sweet or dry, sweet wines being high in sugar content and dry wines containing little or no sugar. Sparkling wines, such as champagne, contain suspended carbon dioxide, the result of bottling the wine before fermentation is complete. Fortified wines, such as port and sherry, contain added brandy. The leading wine-producing countries are France, Italy, Spain, the U.S., Argentina, Germany, Australia, South Africa, Portugal, and Romania

Zinc

Zinc

Metallic chemical element, chemical symbol Zn, atomic number 30.

Zinc is a bluish silver metal, ductile when very pure but brittle otherwise. It forms brass (with copper) and many other alloys. Its major use is in galvanizing iron, steel, and other metals. Zinc is an essential trace element, particularly in red blood cells; in snails, it corresponds to iron in the blood of vertebrates. Zinc oxide is used as a pigment, ultraviolet light absorber (to prevent sunburn), dietary supplement and seed treatment, and photoconductor. Zinc's many other compounds (in which it has valence 2 or, rarely, 1) are used in industrial and consumer applications, including as pesticides, pigments, mordants (see dye), fluxes, and wood preservatives.

Source:britannica encyclopedia

Zircon

Zircon

Crystal Structure of Zircon

Zircon is widespread as an accessory mineral in acid igneous rocks; it also occurs in metamorphic rocks and, fairly often, in detrital deposits. It occurs in beach sands in many parts of the world, particularly Australia, India, Brazil, and Florida, and is a common heavy mineral in sedimentary rocks. Gem varieties occur in stream gravels and detrital deposits, particularly in Indochina and Sri Lanka, but also in Myanmar, Australia, and New Zealand. Zircon forms an important part of the syenite of southern Norway and occurs in large crystals in Quebec.

Source:britannica encyclopedia

Noble gas

Noble gas
Any of the six chemical elements that make up the rightmost group of the periodic table as usually arranged: helium, neon, argon, krypton, xenon, and radon.

All are colourless, odourless, and nonflammable and occur in tiny amounts in the atmosphere (though helium is the most plentiful element in the universe). Their stable electronic configurations, with no unpaired electrons to share, make them extremely unreactive—hence “noble” (i.e., aloof) or inert—though the three heaviest, with outer electrons held less firmly, can form compounds (mainly with fluorine). These gases absorb and give off electromagnetic radiation in a much less complex way than other substances, a property exploited in their use in fluorescent lighting devices and discharge lamps. They glow with a characteristic colour when confined in a transparent container at low pressure with an electric current passing through it. Their very low boiling and melting points make them useful as refrigerants for low-temperature research (see cryogenics)
Source:Britannica encyclopedia

Element chemical

Element,chemical
One of the more than 110 presently known kinds of substances that constitute all matter at and above the level of atoms (the smallest units of any element).

All atoms of an element are identical in nuclear charge (number of protons) and number of electrons (see atomic number), but their mass (atomic weight) may differ if they have different numbers of neutrons (see isotope). Each permanently named element has a one- or two-letter chemical symbol. Elements combine to form a wide variety of compounds. All elements with atomic numbers greater than 83 (bismuth), and some isotopes of lighter elements, are unstable and radioactive (see radioactivity). The transuranium elements, with atomic numbers greater than 92 (see uranium), artificially created by bombardment of other elements with neutrons or other particles, were discovered beginning in 1940. The most common elements (by weight) in Earth's crust are oxygen, 49%; silicon, 26%; aluminum, 8%; and iron, 5%. Of the known elements, 11 (hydrogen, nitrogen, oxygen, fluorine, chlorine, and the six noble gases) are gases under ordinary conditions, two (bromine and mercury) are liquids (two more, cesium and gallium, melt at about or just above room temperature), and the rest are solids. See also periodic table.
Source:Britannica encyclopedia

Periodic Table

Periodic Table
Organized array of all the chemical elements in approximately increasing order of their atomic weight.

The elements show a periodic recurrence of certain properties, first discovered in 1869 by Dmitry I. Mendeleyev. Those in the same column (group) of the table as usually arranged have similar properties. In the 20th century, when the structure of atoms was understood, the table was seen to precisely reflect increasing order of atomic number. Members of the same group in the table have the same number of electrons in the outermost shells of their atoms and form bonds of the same type, usually with the same valence; the noble gases, with full outer shells, generally do not form bonds. The periodic table has thus greatly deepened understanding of bonding and chemical behaviour. It also allowed the prediction of new elements, many of which were later discovered or synthesized. For an illustration of the periodic table, see chemical element.
Source:Britannica encyclopedia

Isotope

Isotope
One of two or more species of atoms of a chemical element having nuclei with the same number of protons but different numbers of neutrons.

They have the same atomic number and hence nearly identical chemical behaviour but different atomic masses. Most elements found in nature are mixtures of several isotopes; tin, for example, has 10 isotopes. In most cases, only stable isotopes of elements are found in nature. The radioactive forms break down spontaneously into different elements (see radioactivity). Isotopes of all elements heavier than bismuth are radioactive; some occur naturally because they have long half-lives.
Source:Britannica encyclopedia

Uranium

Uranium
Chemical element of the actinide series (with many transition element properties), chemical symbol U, atomic number 92.

A dense, hard, silvery white metal that tarnishes in air, it is isolated from such ores as pitchblende. Until the discovery of the first transuranium element in 1940, uranium was believed to be the heaviest element. Radioactivity was discovered in uranium by A.-H. Becquerel. All its isotopes are radioactive; several have half-lives long enough to permit determination of the age of the Earth by uranium-thorium-lead dating and uranium-234–uranium-238 dating. Nuclear fission was discovered in 1938 in uranium bombarded with neutrons, and the self-sustaining nuclear chain reaction, the atomic bomb, and the generation of nuclear power followed. Uranium has various valences in compounds, some of which have been used as colours in ceramic glazes, in lightbulb filaments, in photography, and as dyes and mordants.
Source:Britannica encyclopedia

Liqiud

Liqiud
One of the three principal states of matter, intermediate between a gas and a solid.

A liquid has neither the orderliness of a solid nor the randomness of a gas. Liquids have the ability to flow under the action of very small shear stresses. Liquids in contact with their own vapour or air have a surface tension that causes the interface to assume the configuration of minimum area (i.e., spherical). Surfaces between liquids and solids have interfacial tensions that determine whether the liquid will wet the other material. With the exception of liquid metals, molten salts, and solutions of salts, the electrical conductivities of liquids are small.
Source:Britannica encyclopedia

Solid

Solid
One of the three basic states of matter.

A solid forms from either a liquid or a gas (the other two states of matter) because, as the energy of the atoms decreases, they coalesce in the relatively ordered, three-dimensional structure of a solid. All solids have the ability to support loads applied either perpendicular (normal) or parallel (shear) to a surface. Solids can be crystalline (as in metals), amorphous (as in glass), or quasicrystalline (as in certain metal alloys), depending on the degree of order in the arrangement of the atoms.
Source:Britannica encyclopedia

Arsenic poisoing

Arsenic poisoing

Harmful effects of arsenic compounds (in pesticides, chemotherapy drugs, paints, etc.), most often from insecticide exposure.

Susceptibility varies. Arsenic is believed to combine with certain enzymes, interfering with cellular metabolism. Symptoms of acute arsenic poisoning include nausea and abdominal pain followed by circulatory collapse. Acute exposure to the gas arsine causes destruction of red blood cells and kidney damage; chronic exposure causes weakness, skin disorders, anemia, and nervous-system disorders. Arsenic in urine and hair or nails is the key to diagnosis. Treatment involves washing out the stomach and promptly administering the antidote dimercaprol.

Arsenic

Arsenic

Nonmetallic to semimetallic chemical element, chemical symbol As, atomic number 33.

Photograph:Arsenic (gray) with realgar (red) and orpiment (yellow)

Arsenic (gray) with realgar (red) and orpiment (yellow)

It exists uncombined in two stable (and several unstable) allotropes, one gray and one yellow, but is more often found in nature as the sulfide or oxide. The elemental form is used to form alloys of metals (especially lead), and certain semiconductors are made from crystals of gallium arsenide (GaAs). Arsenious oxide (arsenic trioxide or white arsenic, As2O3) is used in pesticides, as a pigment, and as a preservative of hides and wood; this is the poisonous “arsenic” (see arsenic poisoning) in detective stories. Arsenic pentoxide (As2O5) is also used in insecticides, herbicides, metal adhesives, and pigments.

Argon(noble gas - Ar)

Argon(noble gas - Ar)

Chemical element, chemical symbol Ar, atomic number 18.

Colourless, odourless, and tasteless, it is the most abundant of the noble gases on Earth and the one most used in industry. It constitutes about 1% of air and is obtained by distillation of liquid air. Argon provides an inert gas shield in welding and brazing, in lightbulbs and lasers, in Geiger counters, and in the production and fabrication of certain metals. Because a radioactive form of argon is produced by decay of a naturally occurring radioactive potassium isotope, it can be used to date rocks and samples more than 100,000 years old

Source:Britannica encyclopedia

Aragonite

Aragonite

A carbonate mineral, the stable form of calcium carbonate (CaCO3) at high pressures.

It is somewhat harder and has a slightly higher specific gravity than calcite. Aragonite is found in recent deposits formed at low temperatures near the surface of the earth, as in caves as stalactites, with ore minerals, in serpentine and other basic (see acid and basic rocks) rocks, and in sediments. Aragonite is the mineral normally found in pearls, and it occurs in some animal shells. It is polymorphous (same chemical formula but different crystal structure) with calcite and vaterite, and, with geologic time, changes to calcite even under normal conditions.

Source: Britannica encyclopedia

Antimony (semimetallic)

Antimony (semimetallic)

Semimetallic to metallic chemical element (see metal), chemical symbol Sb, atomic number 51.

 

Of its various allotropes, the most common is a lustrous, bluish, brittle, flaky solid. In nature antimony occurs chiefly as the gray sulfide mineral stibnite, Sb2S3. Pure antimony metal has no important uses, but its alloys and compounds are extremely useful. Some antimony alloys have the rare quality of expanding on solidifying; these are used for castings and for type metal. Alloys with lead are used in car batteries, bullets, and cable sheaths. 

Anti-friction alloys with tin and lead (babbitt metals) are used as components of machine bearings. Antimony compounds (valences 3, 4, and 5) are widely used as flame retardants in paints, plastics, rubber, and textiles; others are used as paint pigments.

Source:Britannica

encyclopedia

Antharcite(coal)

Antharcite(coal)

or hard coal

Coal containing more fixed carbon than any other form of coal and the lowest amount of volatile (quickly evaporating) material, giving it the greatest heat value.

The most valuable of the coals, it is also the least plentiful, making up less than 2% of all coal reserves in the U.S., with most of the known deposits occurring in the East. Anthracites are black and have a brilliant, almost metallic lustre. Hard and brittle, they can be polished and used for decorative purposes. They are difficult to ignite but burn with a pale-blue flame and require little attention to sustain combustion. In the past they were used for domestic heating, but today they have given way to other sources of energy (e.g., natural gas and electricity).

Source:Britannica encyclopedia