Thales (600 B.C.)Thales (600 B.C.) Water

Xenophanes (500 B.C.)Xenophanes (500 B.C.)

Earth Water

EmpedoclesEmpedocles (440 B.C.) (440 B.C.)Four elementsFour elements

EarthEarth

WaterWater

AirAirFireFire

(more commonly called dirt)(more commonly called dirt)

Two Forces shape matter

Love & Strife

Democritus Athens, Greece 400 B.C.Democritus Athens, Greece 400 B.C.

Since Since atomosatomos is the Greek word is the Greek word for “for “indivisibleindivisible” I shall call these ” I shall call these

particles “particles “atomsatoms”.”.

““Atoms” cannot be destroyed, so Atoms” cannot be destroyed, so there is conservation of matter.there is conservation of matter.

The smallest particles of The smallest particles of matter are indivisible.matter are indivisible.

Aristotle Athens, Greece 340 B.C.

Aristotle studied under Plato who also had opinions on chemistry. However, Aristotle had the most influence on the history of chemistry.

Besides chemistry, he also tackled physics, biology, psychology, and logic.

It’s ironic that the theories of Aristotle which were most accepted were also the most incorrect.

His theories that were most correct were mostly ignored.

For example, he correctly classified dolphins as mammals and not fish. It took 2,000 years for biologists to accept this.

For example, he proposed and embraced the mystical fifth element. It took chemists 2,000 years to recognize that there was no mystical fifth element.

First Table of the Elements

Hot Dry

ColdWet

Fifth Element

Quintessence

Philosopher’s stone

Fifth Element makes up the celestial bodies

Gold is the perfect metal.All other metals are less perfect.

The fifth element is so divine that it can turn the lesser (more base) metals into gold.

Elixir of life (a fountain of youth)

Fifth Element

•Matter does not consist of atoms

•Democritus said atoms cannot be divided. You cannot place restraints

on the gods.

Disagree with DemocritusDemocritus

Antoine Laurent Lavoisier France 1793• Lavoisier has been

called the father of modern chemistry.

• Started a system of chemical nomenclature that used ide, -ic & -ous endings.

Examples: Sodium chloride, Ferric oxide and Ferrous oxide

Antoine married the daughter of the tax collector, which helped him pay for his expensive laboratory.

Marie acted as a skilled lab assistant, translator of English science publications, and illustrator for Lavoisier’s experiments

Lavoisier•When heated mercury turned red and absorbed 1/5 of the air.

15

•The amount of “active air” consumed was the same as the amount of “active air” released later.

non-active AirActive AirRoom Air

AzoteOxygen

generateacids

Sulfuric acid

Lived for a while Lived longer Died quickly

S + O2 SO2

2SO2 + O2 2 SO3

SO3 + H2O H2SO4

Table of the Elements (33) Antimony Arsenic Bismuth Cobalt Copper Gold Iron Lead Manganese Mercury Molybdena Nickel Platina Silver Tin Tungstein Zinc

OxygenAzoteHydrogenSulphurPhosphorus Charcoal Muriatic radicalFluoric radical Boracic radical

LimeMagnesiaBarytesArgillSilex

Argill (clay or alum=potassium aluminum sulfate)

Silex (silicon dioxide = quartz

Magnesia (epsom salts=magnesium sulfate)

Lime = calcium oxide

John Dalton England 1796

Elements are composed of minute, indivisible particles called atoms

4. Chemical compounds are formed by the union of two or

more atoms of different elements.

Dalton’s Elements

Arranged from light to heavy by their relative weights

Johan Jacob Berzelius from Sweden

•Older elements take the symbol from their Latin name.

•Fe comes from ferrum not iron.

•Instead of G for gold he wants Au from aurum.

•Instead of S for Silver he wants Ag from argentum.

•Newer symbols come from English names.

•O comes from oxygen.

•2000 experiments over a ten-year period to determine

accurate atomic masses for all the elements now known.

Berzelius’ Symbols for Elements

John Newlands England 1867

Researchers had already began to arrange and classify elements:

Metals vs. non-metalsIn tables of increasing

atomic weight

John Newlands from England had a different way to arrange elements.

Chlorine, bromine & iodine• violently corrosive• form acids

• Lithium, sodium, potassium• Unite violently with oxygen or water• Oxides form caustic aqueous solutions

Every eighth element have similar characteristics Li Be B C N O F Na Mg Al Si P S Cl K Ca ? ? As Se Br

Certain elements resembled one another in behavior.

I call this the “Law of Octaves”

“Law of Octaves”

He presented his theory to the England Chemical Society and was laughed at.

They said to arrange it alphabetically.

Dmitri Ivanovich Mendeleev Russia 1871

Periodic Law

Like Newlands, he used the lithium, sodium, and potassium plus the chlorine family as guide posts

He also saw a periodic repeating of characteristics. However on the third period, he thought there were more than the seven elements that Newlands listed.

Gallium

Germanium

End