Chemical Symbols

1
Chemical Symbols
Formulas
their development and use
2
Greek Symbols
gold mercury copper
silver
iron tin lead
3
Alchemical Symbols

• Each alchemist had his/her own symbols.
• Symbols were designed for handwritten (not
  printed) pages.
• Alchemists were more concerned with secrecy than
  communication.

4
John Daltons System
50. Sulfuric acid 10. Calcium nitrate
Dalton used differently shaped circles for each
element. He then showed compounds as combinations
of these symbols, based on his atomic theories.
5
Jons Jacob Berzelius c. 1815

• He suggested using LETTERS of NAMES as symbols,
  with SUBSCRIPTS. We still do.
• This made type-setting chemical formulas cheaper
  and easier.
• These symbols are UNIVERSAL, and independent of
  the language used for the name.
• A Swedish chemist, most of Berzelius symbols are
  based on Latin names of elements.

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Counting Atoms

• H2O 2 hydrogen, 1 oxygen
• SUBSCRIPTS describe elements they follow.

• Cu(NO3)2 1 copper, 1x22 nitrogen,2x3 6 oxygen
• PARENTHESES work as multipliers, just like
  math.

• CuSO4. 5H2O 1 copper, 1 sulfur, 45 9 O,
  5x210 H
• DOTS act like signs, unlike in math.
• COEFFICIENTS act as multipliers until the
  next dot.

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Problems to Try
Count atoms per element in these compounds.

• Lodestone Fe3O4
• Methanol CH3OH
• Plexiglass CH2CCH3COOCH
• Trinitrotoluene C6H2CH3(NO2)3
• Acetone C(CH3)2O
• Prussian Blue Fe4Fe(CN)63
• Yellow ochre Fe2O3.2H2O
• Lead white 2PbCO3.Pb(OH)2
• Lapus lazuli 3Na2O.3Al2O3.6SiO2.2Na2S
• Paris green Cu(C2H3O2)2.3Cu(AsO2)3
• What do think is meant by this formula for opal
  SiO2.nH2O?

8
Answers

• 3 iron, 4 oxygen
• 1 carbon, 4 hydrogen, 3 oxygen
• 5 carbon, 6 hydrogen, 2 oxygen
• 7 carbon, 5 hydrogen, 3 nitrogen, 6 oxygen
• 3 carbon, 6 hydrogen, 1 oxygen
• 7 iron, 18 carbon, 18 nitrogen
• 2 iron, 5 oxygen, 4 hydrogen
• 3 lead, 2 carbon, 8 oxygen, 2 hydrogen
• 10 sodium, 24 oxygen, 6 aluminum, 6 silicon, 2
  sulfur
• 5 copper, 4 carbon, 6 hydogen, 22 oxygen, 9
  arsenic
• He n means a variable amount