Tuesday, May 17, 2011

Final exam answers to 8 and 31

8) 
           Compounds are polar when the shared electron moves towards the atom with the greater mass. The atom towards which the electron shifts get a S- (slight negative charge) while the other atom contains a S+ (slight positive charge). The polar covalent molecule has two centers of charge and this is known as "dipole". There is great difference in the electronegativity of the atoms. If it were non-polar the electronegativity difference would be zero.
           For a polar molecule is a molecule in which the centroid of the positive charges are different from the centroid of the negative charges. It can also be described as an asymmetric molecule with non-uniformpositive and negative charges. Also called dipole. A polar molecule had a partial positive charge in one part of the molecule and a complementary negative charge in another part. A water molecule is an example of a water molecule (H2O). A water molecule is polar because its O-H bonds are VERY polar, and its bent geometric shape makes the distribution of those polar bonds asymmetrical. The side of the water molecule containing the more electronegative oxygen atom is partially negative, and the side of the molecule containing the less electronegative hydrogen atoms is partially positive. 
          The difference  between covalent bonds/molecules and ionic bonds/molecules is that  in an ionic bond, the atoms are bound together by the attraction oppositely- charged ions. For example, sodium and chloride form an ionic bond, to make NaCl, or table salt. In a covalent bond, the atoms are bound by shared electrons. 


31)


Describe a Beta particle.


A fast-moving electron emitted by radioactive decay of substances. (The emission of beta particles was originally regarded as a ray.)


2 comments:

  1. Great Job Mercedez! On 31, I might add a bit more about what a beta particle is and the charge of it. A beta particle is present in Beta radiation. In Beta radiation, a neutron breaks apart into a proton and an electron, which is released.
    The beta particle is as follows:

    0
    e
    -1

    They symbol for the electron of a beta particle has a subscript of -1 (atomic number), which means it has a negative charge. The subscript 0 (mass number), represents the extremely small mass of the electron compared to that of a proton.

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  2. (sorry about the way the beta particle is written, I couldn't figure out how to write it with the subscripts) The numbers would be on the left side of the e.

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