Chemistry

More Chemistry Information

 

A Little Bit of General Chemistry

 

Electrochemistry and the Corrosion of Steel

Oxidation/Reduction Reactions

Some General Chemical Terminology

Acids and Bases

Compound Definition Example(s)
Acid
  • Traditional inorganic chemistry: Any substance that yields hydrogen ions (H+) in an aqueous solution is called an acid.
  • Expanded definition by J.N Bronsted: Any substance that donates a proton is an acid.
  • Expanded definition by G.N Lewis: An electron acceptor. A substance that presents to the electron pair provided by a base either an acidic acid hydrogen atom or the whole acid molecule. In the latter case, the acid molecule is not a proton "donor" but lacks two electrons in its valence shell.
  • Examples according to traditional definition: HCl, H2SO4, HNO3
  • Examples added by the J.N Bronsted theory: ammonium ion, NH4+, and water, H2O, are also acids.
  • G.N Lewis theory adds: AlCl3, BF3. These compounds are called Lewis acids.
Base
  • Traditional inorganic chemistry: Any substance that yields hydroxyl ions (OH-) in an aqueous solution is called a base.
  • Expanded definition by J.N Bronsted: A base is a proton acceptor.
  • Expanded definition by G.N Lewis: A base is an electron donor.
  • Example according to the traditional definition: sodium hydroxide, NaOH.
  • Examples added by the J.N Bronsted theory: ammonia, NH3, which can add a proton to become ammonium ion, NH4+.
  • Example according to the G.N Lewis theory: trimethylnitride, (CH3)3N. In this case, the nitrogen atom has an unbounded electron pair it can donate. This type of compound is called a Lewis base.

    Note: The Bronsted and Lewis theories of bases are the equivalent: If a substance can accept a proton it must have an unbonded electron pair.