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Old May 15th 2009, 12:36 PM   #1
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Chemistry tutorials & FAQs!

Chemistry is the science branch that studies the structure, the composition and the properties of matter. It also studies the properties of the chemical reactions: the mixture of certain chemical substances and their results. Chemical reaction can be provoked by human, yes, but they can also happen naturally. Two types of reaction exists: the organic and the inorganic reactions. Organic reactions involve organic compounds such as methane.

Example of a well-known chemical reaction (water):
2H2 + O2 → 2H2O

is needed during any chemical reaction. It is needed to break the chemical bonds in the substances. When the new bonds are formed, the energy is released. By comparing the chemical energy of the original substances with the chemical energy of the final substances, you can decide if energy is released or absorbed in the overall reaction.

Two branches of chemical reaction exists: the endothermic reactions and the exothermic reactions (endo/exo means inside/outside, thermic means heat). If the reaction is exothermic, heat will be unleashed from the reaction, which will cause nearby heat around the chemical matter. If, on the other hand, it is endothermic, the matter itself will gain heat.

Example of a well-known exothermic reaction:
The reaction between gasoline and oxygen in a car's inner engine.

Important definitions:
► Matter composed of atoms.
► The smallest particle of an element. It envelopes a positively charged nucleus that is surrounded by electrons.
► Particle charged negatively (-1) and is 1/1836th the size of a proton. They are outside the atom and in constant motion around it. Chemical reaction are, grosso modo, an exchange of electrons.
► Particle in the nucleus with a positive charge (+1).

► A non-charged particle in the nucleus with the same mass of a proton.

Some useful references:

Unit conversion calculator: http://www.chemicool.com/cgi-bin/unit.pl
Basic graphs: http://www.chemicool.com/graph.html

Last edited by Sodapop; Jan 15th 2010 at 07:24 PM.
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