THE DEVELOPMENT OF ATOMIC THEORY Chemistry 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 ( 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”

Aristotle ( BCE) o Famous philosopher of the ancient Greeks o Believed matter was comprised of four elements o Earth, Air, Fire, Water o These elements had a total of four properties o Dry, Moist, Hot, Cold o People liked him – so this idea stayed

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)

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 matter o 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

Procedures of Alchemy o Alchemy brought about many lab procedures o We use some of the same methods and the names developed in these dark ages of chemistry

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

Alchemy had to be discussed in secret so that its students could avoid persecution Alchemical symbols for various materials

Alchemists’ Persecution o Alchemy was tied to witchcraft and druids o it was perceived as heresy by the catholic church o Practitioners had to hide their trade or hobby o Information was passed in code o Coded messages were sent between friends o 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)

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

The relatively quick discovery of things smaller than the once “indivisible” atom The Subatomic Era (1897CE – 1900CE)

 Thompson  Rutherford  Marie Curie  Millikan  Chadwick

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