their development and use
Greek Symbols
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gold mercury copper silver
iron tin lead
Alchemical Symbols
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• Each alchemist had his/her own symbols.
•Symbols were designed for handwritten (not printed) pages.
•Alchemists were more concerned with secrecy than communication.
John Dalton’s System
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50. Sulfuric acid
10. Calcium nitrate
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Dalton used differently shaped circles for each element. He then showed compounds as combinations of these symbols, based on his atomic theories.
Jons Jacob Berzelius c. 1815
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• 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.
Counting Atoms
H2O = 2 hydrogen, 1 oxygen
SUBSCRIPTS describe elements they follow.
Cu(NO3)2 = 1 copper, 1x2=2 nitrogen,2x3= 6 oxygen
PARENTHESES work as multipliers, just like math.
CuSO4. 5H2O = 1 copper, 1 sulfur, 4+5 = 9 O, 5x2=10 H
“DOTS” act like “+” signs, unlike in math. COEFFICIENTS act as multipliers until the next “dot”.
Problems to Try
1. Lodestone Fe3O4
2. Methanol CH3OH3. Plexiglass CH2CCH3COOCH4. Trinitrotoluene C6H2CH3(NO2)3
5. Acetone C(CH3)2O6. Prussian Blue Fe4[Fe(CN)6]3
7. Yellow ochre Fe2O3.2H2O
8. Lead white 2PbCO3.Pb(OH)2
9. Lapus lazuli 3Na2O.3Al2O3.6SIO2
.2Na2S10. Paris green Cu(C2H3O2)2
.3Cu(ASO2)3
11. What do think is meant by this formula for opal: SiO2.nH2O?
Count atoms per element in these compounds.
Answers
1. 3 iron, 4 oxygen2. 1 carbon, 4 hydrogen, 3 oxygen3. 5 carbon, 6 hydrogen, 2 oxygen4. 7 carbon, 5 hydrogen, 3 nitrogen, 6 oxygen5. 3 carbon, 6 hydrogen, 1 oxygen6. 7 iron, 18 carbon, 18 nitrogen7. 2 iron, 5 oxygen, 4 hydrogen8. 3 lead, 2 carbon, 8 oxygen, 2 hydrogen9. 10 sodium, 24 oxygen, 6 aluminum, 6 silicon, 2 sulfur10. 5 copper, 4 carbon, 6 hydogen, 22 oxygen, 9 arsenic• He “n” means “a variable amount”
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