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    Elements Periodic properties 

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    Published on 01-17-2011 12:32 AM
    Categories:
    1. Chemical Reaction

    In chemistry lessons there are many primary materials which will become the mouth of other concepts. One is the concept of the periodic nature of elements.

    Here is a discussion written by colleagues about these topics (if not one hell ... sorry without permission because I want to write too sure so its contents).

    PROPERTIES PERIODICALLY ELEMENTS
    Atom Fingers

    Is the distance from the nucleus to the electrons in the outer shell. The amount of atomic radius is influenced by the size of the atomic number elements.

    The greater the atomic number elements of a party, the more skin the number of electrons, so that the greater the atomic radius.
    So: in one group (from top to bottom), atomic radius larger.

    In one period (from left to right), the atomic number increases, which means the increasing nuclear charge, while the number of electrons fixed skin. As a result the pull the core toward the greater the outer electrons, resulting in increasingly smaller atomic radius.
    So: in one period (from left to right), atomic radius smaller.

    Ionization Energy

    Is the minimum required energy neutral atoms in gas form to let go of one electron to form charged ions +1. If these atoms release electrons to-2 then it will need more energy (called the second ionization energy), and so on. EI 1
    In one group (from top to bottom), ever smaller as the atomic radius increases so that the core attractions of the smaller outer electrons. As a result, the easier it is for the outer electrons are released.

    In one period (from left to right), because of the greater atomic radius so that the smaller the core attractions of the outermost electron bigger / stronger. As a result the outer electrons become increasingly difficult to be released.

    Electron affinity

    Is the energy released or absorbed by neutral atoms in gas form when receiving an electron to form negative ions. The more negative electron affinity prices, the easier the atomic receive / attract electrons and also the more reactive element.

    Electron affinity is not the opposite of ionization energy. In one group (from top to bottom), the price of the smaller electron affinity.
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    Titration 

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    admin
    Published on 01-16-2011 01:56 AM  Number of Views: 292 
    Categories:
    1. Chemical Reaction
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    Titration Also called volumetric is a method of the fast chemical analysis , accurate and often used to determine the content of an element or compound in solution. Titration was based on a reaction which is described as:

    aA + bB ---> reaction Result

    Where
    A: Titrator/Reagent/Titran a known concentration (a standard solution) and volume is used to react with a solution of the analyte.
    B: Titrand whose concentration is not known
    Volumetric (titration) done by adding (reacting) a given volume (usually from a burette) standard solution (of known concentration with certain) necessary to react completely with a solution of unknown concentration . For know the reaction is complete, then use indicator solution were added into the solution is titrated.

    Standard solution called the titrant. If the volume of standard solution is known from experiment, the concentration of compounds within the solution of the unknown can be calculated by following equation:

    VA x NA = VB x NB

    Where:
    NB = solution concentration of the unknown concentrations
    VB = volume of the solution of unknown concentration
    NA = concentration of solution of known concentration (standard solution)
    VA = volume of solution of known concentration (standard solution)
    In doing titration may take a few requirements that must be considered, like;
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