THE DEVELOPMENT OF ATOMIC THEORYChemistry Rules!

Philosophical Era (Ancient Greece)

o Two ancient Greeks stand out in the advancement of chemistry.

o Their ideas were purely based on reason, without experimental support (as was common in that time)

Democritus (460-370 BCE)

o The most well-known proponent of the idea that matter was made of small, indivisible particles

o Called the small particles “atomos” meaning “that which cannot be divided”

o Believed properties of matter came from the properties of

the “atomos”

Philosophical Era

Aristotle (384-322 BCE)

o Famous philosopher of the ancient Greeks

o Believed matter was comprised of four elementso Earth, Air, Fire, Water

o These elements had a total of four propertieso Dry, Moist, Hot, Cold

o People liked him – so this idea stayed

Philosophical Era

Philosophical Era

The “Dark Ages” of Chemistry where early chemists had to work in secret and encode their findings for fear of persecution

Alchemical Era (300 BCE ~ 1400CE)

Alchemical Era (300 BCE ~ 1400CE)

o the closest thing to the study of chemistry for nearly two thousand years

o based on the Aristotelian idea of the four elements of mattero If you change the properties, then you could

change elements themselves – lead to gold and immortality

o Very mystical study and experimentation with the elements and what was perceived as magic

o Study was persecuted, findings hidden in code

Alchemical Era

Procedures of Alchemyo Alchemy brought

about many lab procedures

o We use some of the same methods and the names developed in these dark ages of chemistry

Alchemical Era

Elements in Alchemyo Alchemists

studied many different materials, and their properties, in order to find a way to turn lead into gold and achieve immortality

Alchemical Era

Alchemy had to be discussed in secret so that its students could avoid persecution

Alchemical symbols for various materials

Alchem

ical Era

Alchemists’ Persecutiono Alchemy was tied to witchcraft and druids

o it was perceived as heresy by the catholic churcho Practitioners had to hide their trade or hobby

o Information was passed in codeo Coded messages were sent between friendso Symbols were used to avoid readable words

o The growth of Chemistry was stunted by the oppression endured during this era

(No such problems in the Far East –Hence gunpowder)

Alchemical Era

The printing press heralds the widespread transfer and acquisition of knowledge

The Classical Era (1400CE – 1987CE)

Dalton Boyle Cavendish Priestley Gay-Lussac Newton Lavoisier Avagadro Mendeleev Proust

Classical Era

The relatively quick discovery of things smaller than the once “indivisible” atom

The Subatomic Era (1897CE – 1900CE)

Thompson Rutherford

Marie Curie Millikan Chadwick

Subatomic Era

The Quark Era starts in 1964, but that advance can be regarded as outside the realm of chemistry – instead a part of nuclear physics

The Modern Era (1900CE – Present)

Plank Bohr Heisenburg DeBroglie Schrödinger

Modern Era