History of Chemistry

• Practical Arts and Crafts (---to 600 B.C.E.)• Greek Period (600 to 300 B.C. E.)• Alchemy (300 B.C.E. to 1650 C.E.)• Phlogiston (1650 to 1790)• Modern Chemistry (1790--- )• Note: This listing focuses on the Middle

East and Western Europe. Dates are very approximate

Practical Arts and Crafts

Variations found in almost all cultures

Practical uses of Chemistry in “everyday life”Pottery, baking, brewing, medicines, extracting metals from ores

Empirical focus:what works--did not ask why

Greek Period

Philosophical approach

Attempt to understand principles that would explain the universe

Not supported by empirical evidence

Not supported by experimental data

Alchemy

Combined Greek philosophical tradition with practical Egyptian craft tradition

Mixed astrology and mysticism and Greek philosophical tradition with practical knowledge

Alexandria (331 BCE) had greatest library of ancient times, including books with diagrams of chemical equipment and processes

Main focus of Alchemists

Search for philosopher’s stone (elixir of life)

confer immortality

transmute base metals into gold

Later emphasis on Iatrochemistry (medicinal chemistry)

Spread of Islam after 640 CE brought Arab influence to many areas surrounding the Mediterranean and mid-east

These areas were much more advanced than Western Europe (still in the Dark Ages)

Centers of Learning in Spain and other areas

Never found the philosopher’s stone, but acquired much practical information about chemistry

Phlogiston Era

Stahl thought that there was a “fire principle” called phlogiston in anything that would burn

Phlogiston would be released when it burned

Wood → Ash + Phlogiston (into air)

Wood → Ash + Phlogiston (into air)

Ashes weigh less than wood

Metals → Calx + Phlogiston

Calx often weighed MORE than metals

Contradictory information here—Can removing something both lower andraise weight?

Mg + O2 → MgO

Now know that oxygen from air reacts with metals such as Mg to form a new compound MgO

2 Mg + O2 → 2 MgO (balanced)

Modern Chemistry

Robert Boyle – The Skeptical Chymist 1661

Relied on Expermental Evidence

Lots of information developed during the intervening years

Antoine Lavoisier (1743-1794)

Carefully weighed materials before and after burning (closed container)

Elementary Treatise on Chemistry---1789

Chemistry described in “modern” terms

Law of Conservation of Matter (Mass)

Matter cannot be created or destroyed by ordinary chemical means