|MadSci Network: Chemistry|
Hi: Sodium is a metal that reacts explosively with water, check out this site for some properties: http://www.ilpi.com/msds/ref/alkalimetal.html Chlorine is a yellow-green poisonous gas whose MSDS can be found here: http://msds.pdc.cornell.edu/msds/siri/msds/h/q114/q287.html Compounds do not exhibit the properties of the individual elements. so, sodium chloride does not exhibit the properties of sodium or chlorine. NaCl (sodium chloride, or table salt) has a long history. Mentioned in the bible as collateral for trade, it was highly prized. It has become a very common substance now. We not only like sodium chloride in our diet, we need it to help maintain fluid controls and aid in muscular contractions. The MSDS for NaCl can be found here: http://www.syndel.com/msds/nacl_msds.htm When sodium and chlorine are reacted, there is a transfer of electrons. Na (sodium) gives away an electron and becomes Na+ (sodium ion). The sodium ion does not have the properties of its parent atom, solid sodium metal. The electron that is given away goes to chlorine, which needs only one elctron to complete its outer shell. Chlorine accepts the electron and becomes Cl-, or chloride ion. Again, the chloride ion does not act at all like its parent atom, chlorine. Sodium ion and chloride form an electrostatic bond, they are attracted to each other because they carry opposite charges, one is plus and one is minus. When sodium chloride is dissolved in water, a process called solvation occurs. Water is a polar solvent. The water molecule has a positive end and a negative end, very similar to the opposite sides of a car battery. The positive part of the water molecule is attracted to the negative part of the sodium chloride, the chloride ion. The negative part of the water is attracted to the positive part of the sodium chloride, the sodium ion. Thus, the sodium chloride dissociates, or breaks apart in water. (Dissociate is the opposite of associate) If the water evaporates, the sodium ion and chloride are forced closer and closer, due to evaporating media. When they get close enough, the attraction is great enough to associate them again. The key here is that sodium (Na) and sodium ion (Na+) do not have similar properties. Same for chlorine and chloride. Therefore when Sodium chloride dissociates in water, sodium and chlorine is not formed. Sodium ion and chloride are formed, two very different acting things. Hope this helps. tc Chemistry, The Central Science: Brown, LeMay, Bursten, 8th edition, Prentice Hall publishers.
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