The Development of atomic theory

1. The Development of atomic theory Chemistry Rules!

2. Philosophical Era (Ancient Greece) • Two ancient Greeks stand out in the advancement of chemistry. • Their ideas were purely based on reason, without experimental support (as was common in that time)

3. Philosophical Era Democritus (460-370 BCE) • The most well-known proponent of the idea that matter was made of small, indivisible particles • Called the small particles “atomos” meaning “that which cannot be divided” • Believed properties of matter came from the properties of the “atomos”

4. Philosophical Era Philosophical Era Aristotle (384-322 BCE) • Famous philosopher of the ancient Greeks • Believed matter was comprised of four elements • Earth, Air, Fire, Water • These elements had a total of four properties • Dry, Moist, Hot, Cold • People liked him – so this idea stayed

5. Alchemical Era (300 BCE ~ 1400CE) The “Dark Ages” of Chemistry where early chemists had to work in secret and encode their findings for fear of persecution

6. Alchemical Era Alchemical Era (300 BCE ~ 1400CE) • the closest thing to the study of chemistry for nearly two thousand years • based on the Aristotelian idea of the four elements of matter • If you change the properties, then you could change elements themselves – lead to gold and immortality • Very mystical study and experimentation with the elements and what was perceived as magic • Study was persecuted, findings hidden in code

7. Alchemical Era Procedures of Alchemy • Alchemy brought about many lab procedures • We use some of the same methods and the names developed in these dark ages of chemistry

8. Alchemical Era Elements in Alchemy • Alchemists studied many different materials, and their properties, in order to find a way to turn lead into gold and achieve immortality

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

10. Alchemical Era Alchemists’ Persecution • Alchemy was tied to witchcraft and druids • it was perceived as heresy by the catholic church • Practitioners had to hide their trade or hobby • Information was passed in code • Coded messages were sent between friends • Symbols were used to avoid readable words • The growth of Chemistry was stunted by the oppression endured during this era (No such problems in the Far East –Hence gunpowder)

11. The Classical Era (1400CE – 1987CE) The printing press heralds the widespread transfer and acquisition of knowledge

12. Classical Era • Dalton • Boyle • Cavendish • Priestley • Gay-Lussac • Newton • Lavoisier • Avagadro • Mendeleev • Proust

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

14. Subatomic Era • Thompson • Rutherford • Marie Curie • Millikan • Chadwick

15. The Modern Era (1900CE – Present) The Quark Era starts in 1964, but that advance can be regarded as outside the realm of chemistry – instead a part of nuclear physics

16. Modern Era • Plank • Bohr • Heisenburg • DeBroglie • Schrödinger