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Old 05-03-2009, 07:25 AM
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Default Carbon && Carbon Dioxide

so pinky take this,,which class r u in???on that basis i may tell u more ...
After reading tell how did u like it....

CARBON

Carbon (pronounced /ˈkɑrbən/) is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5730 years.[4] Carbon is one of the few elements known to man since antiquity.[5][6] The name "carbon" comes from Latin language carbo, coal, and, in some Romance and Slavic languages, the word carbon can refer both to the element and to coal.

There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon.[7] The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent, while graphite is opaque and black. Diamond is among the hardest materials known, while graphite is soft enough to form a streak on paper. Diamond has a very low electrical conductivity, while graphite is a very good conductor. Under normal conditions, diamond has the highest thermal conductivity of all known materials. All the allotropic forms are solids under normal conditions but graphite is the most thermodynamically stable.




CARBON DIOXIDE

Carbon dioxide (chemical formula: CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.

Carbon dioxide is used by plants during photosynthesis to make sugars which may either be consumed again in respiration or used as the raw material to produce polysaccharides such as starch and cellulose, proteins and the wide variety of other organic compounds required for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend on living and decaying plants for food, either directly or indirectly. It is, therefore, a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Large amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.

As of March 2009[update], carbon dioxide in the Earth's atmosphere is at a concentration of 387 ppm by volume.[1] Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared.

Carbon dioxide has no liquid state at pressures below 5.1 atm. At 1 atm the gas deposits directly to a solid at temperatures below -78 °C and the solid sublimes directly to a gas above -78 °C. In its solid state, carbon dioxide is commonly called dry ice.

CO2 is an acidic oxide: an aqueous solution turns litmus from blue to pink.

CO2 is toxic in higher concentrations: 1% (10,000 ppm) will make some people feel drowsy[citation needed]. Concentrations of 7% to 10% cause dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour
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