ChemHistory

transcript

A Chemhistory

Lesson

Paul D. Price

Trinity Valley School

pricep@trinityvalleyschool.org

What We Do Is Hard!

• Memorization vs. Understanding• Various Levels of Abstraction• Critical Thinking• Putting it all together

The Use of History

• Puts Discoveries in Context– When?– Why Then?– How?

• The Human Element– I can do this

• Aligns with “Classic” Chem course – 2010 TEKS

The Organizing Principle

• When?

• Who?

• Why Then?

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Dalton!?

• The mass of atoms?– Needs

Joseph Black (1728 - 1799)

• Analytical Balance

• Specific + Latent Heat

• Fixed Air (1754)– CaO + CO2 --> CaCO3

– Ca(OH)2 + CO2 --> CaCO3 + H2O

– MgCO3 + HCl --> H2O + CO2 + MgCl2

Pneumatic Chemistry

• H2 (1766) by Cavendish• O2, HCl, NH3, NO, N2O, SO2 by

Priestley (1774 - 86?)• Cl2 and O2 by Scheele (17??)• Lavoisier (O2 ?)

– Conservation of Mass

Proust and Dalton

Nuts and Bolts

Cup 10 is BN. Can you figure out the rest?

Can you explain the data?

• All Matter is made up of indivisible particles called atoms.

• All atoms of the same element are exactly the same; atoms of different elements are different in some fundamental way

• Compounds form when atoms of different elements combine in unique fixed ratio

• In a chemical reaction, atoms are simply rearranged to create new compounds from old

Sample Homework

The Real Payoff

• CO

• One O weighs 1.33 times more!

• Define C = 1, O = 1.33

• Define C = 100 , O =

• Define C = 12, then O = 16133

A Small ProblemCompound Grams of

HydrogenGrams of Oxygen

Possible Formula

A 2.000 15.84

B 103.00 815.84

Rule of Greatest Simplicity

Dalton Mass Table

O = 7.92

Gay-Lussac

• 2 vol H + 1 vol O = 2 vol water

• 3 vol H + 1 vol N = 2 vol ammonia

• 1 vol N + 1 vol O = 2 vol nitric oxide

Diatomics!

Future Developments

• Electrochemistry and diatomic bonding

• Why only H2? (not Hn)

• Organic Chemistry and Empirical vs. Molecular Formula

• Excellent Atomic Weights (Cannizzaro)

Periodic Table

• 6.02 x 1023

References• Arnold B. Arons; Development of Concepts of

Physics• Aaron J. Ihde; The Development of Modern

Chemistry• Classic Chemistry;

http://web.lemoyne.edu/~giunta/• Classic Papers from the History of Chemistry;

http://www.chemteam.info/Chem-History/Classic-Papers-Menu.html

Thank you Dennis

ChemHistory

Education