(COVALENT BONDS)



Gilbert Newton Lewis invented the idea of covalent bond.



Covalent bonding occurs when two non-metallic atoms in a molecule share electrons so that both of the atoms fill their outer shells. These electrons are shared in one or more pairs called electron pairs; each pair is a covalent bond. (Beiser pg 161)



Theories of chemical bonds go back a long time. One of the first was developed by Roman poet Lucretius between 55- 95B.C. , author of De Rerum Natura is the title that means on the nature of things. In this poem, Lucretius described atoms as tiny spheres with fishhook-like arms. Atoms combined with each other, according to Lucretius, when the hooked arms of two atoms became tangled with each other.
(http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/valenceframe.html)




There are numerous methods in which atoms can combine or chemically bond together to form a molecule. The most common type is covalent bonding, where the atoms share pairs of outer shell or valence electrons. Covalent bonding may be single or multiple, depending on the number of pairs the atoms share.

Ionic bonding is another common way atoms combine, where one atom passes its electron to the other element, creating positive (+) and negative (-) ions.

Example-
Salt or Sodium Chloride (NaCl) is a good example of a ionic bonding. Sodium (Na) has 1 valance electron and Chlorine (Cl) has 7 electrons in its outer orbit. If Sodium lost its valance electron, its next shell will be full. But that would also make Sodium a positive ion. If Chlorine gained 1 valance electron, its shell would be full with a maximum of 8 electrons, and it would then be a negative ion. Mcmurry, pg 12

Thus Sodium Chloride (NaCl) is a bonding of the Na+ ion and the Cl- ion.

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Words to Know for bonding

Covalent bond: A chemical bond formed when two atoms share one or more pairs of electrons with each other.

Double bond: A covalent bond consisting of two pairs of electrons.





Application of (Topic)


Covalent boding are used when we are frying a egg, and was also used a weapon in world war 1. The water we bathe, clean, and cook with are also related to covalent bonds. Proteins are formed by one or several polypeptide chains.http://www.proteincrystallography.org/protein/





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References

  1. Beiser, A. (1988). Physical Science (2nd Edition). New York, NY: McGraw Hill
  2. (Ref #2 - from internet)http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/valenceframe.html
  3. Mcmurry John (1984) ORGANIC CHEMISTRY. Belmont, Calfornia
4. http://www.scienceclarified.com/Ca-Ch/Chemical-Bond.html#ixzz1TAqI
5. http://www.proteincrystallography.org/protein/

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