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”