September 10, 2001
Chemistry 100

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Sodium, Na

• Symbol from Latin Natrium
  • related, in turn, for words for salt
• the ELEMENT wasn't isolated intil the 1800's
• Sodium is a low density, silver colored metal
  • It floats on water
• Sodium is very soft; can be cut with a plastic knife

Sodium seems best known as a very reactive metal

• Tarnishes (oxidizes in air) in a few minutes
• Reacts violently with water
  • Produces H₂ gas that often catches fire
  • reaction produces a lot of heat

Sodium chemistry is actually very boring, except for very rare cases involving the metallic element

• Virtually all sodium is found as ionic sodium compounds
  • Sodium atoms lose one electron and become Na⁺
  • Positive Ions are known as CATIONS
  • There will always be an equal negative charge from ANIONS
  • Sodium Chloride (table salt, rock salt) is NaCl
    • Actually consists of Na+ ions and Cl- ions
    • Ions are arranged on a crystal lattice
    • If you dissolve salt, the crystal disappears and solution contains Na+ and Cl- Ions
  • Note that there are no Na-Cl molecules.
  • It's easy to form other sodium compounds
    • just add other negative ions
      • For most chemistry, the sodium is a spectator (goes along for the ride)-- it stays Na+ ion
      • As a rule, the chemistry changes very little if we replace the Na+ ion with other ions.
      • Na salts are often used, mainly because sodium compounds are less expensive than other salts.

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  Uses of Sodium

  • We use vast quantities of sodium compounds, mainly sodium chloride
    • Derived by evaporting sea water or from underground mineral deposits
    • The city of Detroit lies on top of massive salt mines click here for Detroit Salt
    • The salt deposits are the result of trapped seawater evaporating millions of years ago.
  • Large amounts of Sodium Carbonate are used in glassmaking
    • We demonstrated the bright orange color from heated sodium (ions or atoms)
  • Very little Sodium metal is used directly
    • There is one application which is a good candidate for the Element Quest Assignment. Available at the Hardware Store and can be seen driving around town. The first word of the product is Sodium ....

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