CARNIVAL OF CHEMISTRY: THE CONCEPT OF SUBSTANCE ...
Thursday, February 17, 2011
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The second edition of the Carnival of chemistry approaches, Feb. 23 is approaching and I invite anyone who reads this blog post to go on
The second edition of the Carnival of chemistry approaches, Feb. 23 is approaching and I invite anyone who reads this blog post to go on
Scientific
to host this round of the carnival. It was also recently opened the site
http://www.carnevaledellachimica.it/ The chemicals also can be divided to 
a) the nature of their constituent atoms (CO2, NH3, etc. ...). c) Inventory report for the different space, if you are made of the same type of atoms and the same ratio. elementary substances can be defined, namely those consisting of atoms of the same species (same atomic number) and compounds derived from the combination detereminati atomic ratio of at least two different elements. The elementary substances can be formed by single atoms such as noble gases, helium (He) colorless and odorless, has the lowest boiling point among all the elements and can only be solidified if exposed to very high pressures, and has various applications, including ; being used by divers to dilute the oxygen content in the cylinders, Ne (neon), etc. ... Discrete aggregates of atoms, that is, separate units and separate from each other, each of which consists of two or more atoms bonded together, an example? oxygen one of the most common chemical elements in the earth's crust. It has a high ability to bind to almost all of the elements, hence the term oxidation is coinvoto in the formation of a large amount us compounds, it creates oxides, peroxides, super oxides or hydroxides. Participates in the formation of carbon dioxide (CO2), alcohols (R-OH), aldehydes (R-CHO), and carboxylic acids (R-COOH). oxygen radicals - such as chlorates (ClO 3-), the perchlorates (ClO4-), chromates (CrO42-), the dichromates (Cr2O72-), the permanganates (MnO4-), and nitrates (NO3-) - all oxidizing agents. Many metals such as iron bind to oxygen atoms, resulting in several compounds such as iron oxide (3 +) (Fe2O3), commonly called rust.
addition to the O2 molecule, the oxygen can be found in the atmosphere to form ozone (O3). Atri examples, iodine, phosphorus, sulfur, the latter two belong to the group of macronutrients and are components of fundamental importance in the synthesis of organic molecules. The substance can also be made of a continuous set of atoms linked together by covalent bonds, such as carbon in graphite or diamond, or by ties of sodium metal types, zinc, copper etc. ... The separate units are the substances they are monoatomic, polyatomic molecules are called. The
elementary substances can be classified as molecular, polymer, metal.
compounds can be formed by molecules like carbon dioxide, oxygen, methane, water, ammonia, etc. ... by concatenation of atoms (silicon dioxide, for example ..) or ions (atoms or groups of atoms that have transferred electrons, and positive as Na, Ca, NH4, or have purchased the negatives such as Cl, CO3-, NO-held together by electrostatic forces between charges of opposite sign (eg calcium chloride, sodium carbonate, ammonium nitrate). elementary substances can be classified as molecular, polymer, metal.
An example of widely used compounds are phenols, compounds containing a hydroxyl group attached to a benzene ring
.
are widely distributed in nature, thymol and vanillin are important constituents of vanilla beans and thyme, respectively.
a reaction of fundamental importance that happens in every living system, in food and many other materials that contain C = C double bond is
auto-oxidation (a process that requires oxygen and no other reagent).
The autoxidation is a radical chain process that converts a group RH ROOH in a group called hydroperoxide. The process begins with the removal of a hydrogen atom with an electron from a carbon allyl. Losing the proton with the electron carbon has only seven electrons in its valence shell, one of which is spaiato.Un molecoa atom or a radical with these characteristics is defined. Idrperossidi The compounds are unstable and biological conditions are degraded to aldehydes and carboxy acids cprta to chain them turn cause the unpleasant smell of "rotten". Fortunately, in nature there are various defenses, such as vitamin E, which has a phenolic nature, ascorbic acid (vitamin C) glutathione, against the formation of radicals annoying. In fact in many foods such as BHT are added phenol to retard deterioration due dell'autossidazione.
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