|Questions||Objectives||1. Alchemy to Chemistry|
|2. Paracelsus||3. Johann Van Helmont||4. Robert Boyle|
|5. Phlogiston||6. Lavoisier and the Chemical Revolution||7. Electrolysis & New Elements|
Before we are done with this program we will have seen the transition from alchemy to chemistry as the reigning paradigm on the nature of matter and changes which it undergoes. We will see the role of two transitional characters and the influence they had on the development of chemistry as a science distinct from alchemy and its spiritualism. We will see how a speculative, but essentially correct, book changed the paradigm virtually overnight by defining what is meant when we speak of an "element". We will examine two competing theories on the nature of combustion and see how the concept of the weight of atoms led to a revolution in chemistry. Finally we will briefly examine the role of electricity, newly discovered and little understood, in the discovery of new chemical elements.
1. Describe the major factors which led to a transition from alchemy to chemistry in the seventeenth and eighteenth centuries.
2. Who was Paracelsus and what did he contribute to the science of chemistry.
3. Who was van Helmont and why is he sometimes called "the First Chemist"
4. What did Robert Boyle contribute to our modern concept of "element".
5. Simplify the distinction between the concept of element as envisioned by Aristotle, Alchemy, and Boyle
6. How did Boyle's concept of "element" differ from that of Aristotle and from an alchemist's?
7. What is phlogiston and what were its properties thought to be?
8. Why was Lavoisier's weighing of substances important?
9. Why is Lavoisier remembered as the "father" of chemistry?
10. How did Lavoisier determine that a substance was not an element?
11. Who discovered oxygen, Priestly or Lavoisier? Explain.
12. Why was the invention of the battery important in the history of chemistry?
13. Who was Humphrey Davy, and what did he do?
1. Characterize the transition from alchemy to chemistry through the concept of element
2. Compare and contrast the views on matter of Paracelsus, van Helmont and Boyle
3. Describe the phlogiston theory of combustion
4. Specify the contributions of Lavoisier to the chemical revolution
5. Describe the role of the battery in the discovery of chemical elements
1.1.1. reaction products completely new
1.1.2. nothing remained of the old substance (reactant) except a "virtue" or hidden quality
1.2.1. a substance was white because it contained "form of whiteness"
1.2.2. substances were endowed with personality: they loved and hated (affinities)
1.4.1. quantitative studies come to chemistry
1.4.2. indestructibility of matter realized
1.4.3. nature of acids and bases and their salts began to be understood
2.3.1. slept on the floor of taverns
2.3.2. coined the word "alcohol"
2.7.1. publicly burned the works of Galen to show his contempt for orthodox medical opinion
2.7.2. considered the views of Aristotle and Galen to be those of heathens and heretics
2.7.3. known for original ideas and violence of temper
2.7.4. wandered around Europe engaging in stormy controversies with physicians who followed the theories of Galen
2.7.5. lectured in vernacular Germans rather than Latin
2.7.6. aroused such violent opposition that his writings could not be published until twenty years after his death
2.8.1. it is not altogether clear exactly what his ideas were in many cases
2.9.1. alchemy meant any process in which natural products were mad fit for a new end, processes such as working iron and baking bread
2.9.2. held that the macrocosm (the universe) and the microcosm (man) behaved similarly, so human digestion was also a human process
2.9.3. controlled by an alchemist spirit he called "the Archaeus"
2.9.4. The Archaeus separated poisonous substances from nutritious ones in the body
2.9.5. the most important goal of alchemy was the preparation of medicines called "arcana" which could restore bodily balance disturbed by disease
2.9.6. believed in transmutation, but not as the primary goal of alchemy
2.10.1. grew up in mining district with good knowledge of metallurgy
2.10.2. obtained a series of salts of various metals in solution
2.10.3. called them "oils"
2.10.4. thus generalized chemical reactions instead of considering every process as an individual treatment of a separate substance
2.10.5. greatly increased the number of remedies available, although some were distinctly dangerous to the patient
2.11.1. ideas encountered strenuous opposition by physicians, ideas were spread by a large group of followers
2.12.1. added salt to tradition of mercury and sulfur as components of metals
2.12.2. concrete expression of the idea of soul, spirit, and body (gas, liquid, solid)
2.12.3. added body to complete the triangle
2.12.4. air (called "chaos" by Paracelsus) had given way to fire as the prime principle
2.12.5. sulfur embodied fire, mercury embodied liquidity, salt embodied earth
2.12.6. when wood burns "that which burns is sulfur, that which vaporizes is mercury, that which turns to ashes is salt."
2.12.7. fitted so well with observations that it completely replaced the sulfur mercury theory
2.12.8. Paracelsus still considered the four elements of Aristotle as basic, but placed little emphasis on them and that his sulfur, mercury, and salt were not the common substances but rather their more abstract essences. The four elements appeared in bodies as three principles of salt, sulfur, mercury
184.108.40.206. everything had its own particular kind of salt, mercury and sulfur
220.127.116.11. salt: principle of fixity and incombustibility: earthiness
18.104.22.168. mercury: principle of fusibility and volatility: metalness
22.214.171.124. sulfur: principle of combustibility
2.12.9. medical substances were composed from the four elements, which formed receptacles or matrices for the universal qualities of the tria prima or three prime qualities
"The world is as God created it. He founded this primordial body on the trinity of mercury, sulfur and salt and these are the three substances of which the complete body consists. For they form everything that lies in the four elements, they bear them all the forces and faculties of perishable things.
3.5.1. Spain was in control of what is now Belgium
3.17.1. planted tree in weighed amount of earth
3.17.2. watered it for 5 years
3.17.3. tree gained 164 pounds, weight of earth remained the same
3.17.4. concluded that wood was made from water alone
3.19.1. fused a weighed amount of sand with alkali to form water glass
3.19.2. water glass liquefied when exposed to air, obviously a conversion of earth to water
3.19.3. water could be reconverted to earth by treatment with acid and the amount of earth (silica) recovered was the same as the original amount
3.20.1. quantitative: routing weighing of reactants, hinted at conservation of mass
3.20.2. theory of the elements: when water evaporates it gives rise to an airlike substance, so do many chemical reactions. These could not be air, so represent a new class of materials. The product of evaporation of water easily returned to water, so Van Helmont considered it a type of vapor. Other substances were more permanent so he gave them a name.
"I call this spirit, unknown hitherto, by the new name of Gas, which can neither by contained by vessels, nor reduced into a visible body . . ."
3.20.3. 'gas' comes from 'chaos'
3.20.4. gas was subtler than a vapor, but denser that elementary air
3.20.5. chemical reactions can produce gas powerful enough to explode a closed glass container, used it to explain the effects of gunpowder.
4.6.1. pressure is inversely proportional to volume
4.8.1. a dialogue between supporters of the older theories and Boyle, who needed to be convinced by more that medieval speculations
4.8.2. presented convincing arguments to destroy most of the former beliefs
4.8.3. did not present a substitute for the ideas which were cast aside
4.8.4. led some to believe that he was a complete skeptic
4.8.5. supported corpuscular theory of matter
126.96.36.199. conceived of small, solid, physically indivisible particles tat were the building blocks of nature. These were associated into larger groups which often acted as units through a number of chemical reactions. Size and shape of these units gave physical properties to substances, but their motion was equally important, and a change of motion resulted in a change in properties. Attraction and affinity were explained by the mutual fitting together of moving particles.
4.8.6. defined modern view of element, although he still believed in transmutation by rearranging corpuscles
188.8.131.52. did not make connection between corpuscles of matter and purity of elements
4.8.7. "I now mean by elements . . . certain primitive and simple or perfectly unmingled bodies, which not being made of any other bodies or of one another, are the ingredients of which all those perfectly mixt bodies are immediately compounded and into which they are ultimately resolved."
4.8.8. Began dialogue on modern concept of element
184.108.40.206. much as Galileo did with motion
220.127.116.11. dispelled alchemists notion of element
18.104.22.168. elements as purity of substance replaced substances as "purveyors of elemental principles"
4.8.9. Boyle was not clear on how to distinguish elements from other substances
22.214.171.124. listed no possible candidates
126.96.36.199. 17th century techniques were crude
188.8.131.52. many "elements" were really "compounds"
184.108.40.206. how could a chemist tell if a material was "unmingled" or "mixt"?
5.6.1. combustion ceased when air became saturated with phlogiston
5.6.2. combustion ceased when substance "ran out of" phlogiston
5.6.3. phlogiston was removed from air by plants which were eaten by animals
5.6.4. a phlogiston cycle
5.11.1. weight is a physical process which was thought to be separate from chemical changes
5.11.2. not so obvious to 17th and 18th century chemists
5.11.3. high temperatures attained with lenses actually vaporized some of the calx so weight gain was not apparent
5.12.1. phlogiston as incorporeal, ethereal fire, substance with negative weight, lightest known substance
5.12.2. too many problems arose, signaled eventual end of the theory
6.1.1. unfortunate association with a company organized to collect taxes for King Louis
6.1.2. died at guillotine (of no use to the New Republic of France)
6.1.3. headless body buried in unmarked grave
6.2.1. invented precise scale to weigh small amounts of matter
220.127.116.11. accurate to 0.0005 grams
18.104.22.168. about 1/100 of a drop of water
6.2.2. mass of all reactants = mass of all products
6.2.3. cannot create matter from nothing, can only change form
6.2.4. matter is not created from nothing, only changes form during chemical reactions
6.3. freed thinking from phlogiston theory
6.3.1. Priestly's Dephlogisticated Air
6.3.3. showed that products of combustion weighed more than combustible materials
6.3.4. combustion is a process of addition rather than subtraction
22.214.171.124. involves combination with oxygen in air
6.3.5. "discovered" oxygen (recognized it as a substance)
6.4.1. If a reaction produces a product that weighs more than the reactant then the product cannot be an element
6.4.2. smaller weight represented the uncombined substance
6.4.3. recall Boyle's definition of an element
6.6.1. Traite Elementair de Chimie (1789)
6.6.2. made clearly defined list of elements based on Boyle's criteria
6.6.3. put discoveries of others in coherent form for the first time
6.6.4. took mystery out of chemistry
6.6.5. many errors but great advancement of concept and method
7.2.1. by Alessandro Volta (1745-1827)
7.2.2. allowed continuous supply of electricity
7.2.3. from Galvani's observation
126.96.36.199. dead frogs twitching
188.8.131.52. hung on wire, touching lower wire
184.108.40.206. Galvani reasoned a new kind of life energy
220.127.116.11. Volta recognized reaction between two metals mediated by electrolyte
7.2.4. Voltaic Pile: The First Battery
7.3.1. decomposed water into hydrogen and oxygen
7.3.2. more current and more time = more water decomposed
7.3.3. recombined to form water again
7.3.4. showed water is not an element
7.3.5. related electricity to chemistry
7.4.1. electrolyzed molten salts
7.4.2. discovered potassium, sodium, barium, strontium, calcium, magnesium
7.4.3. all are shiny and reactive metals, reacted rapidly with air or water
7.4.4. became an invalid at age 33 due to habit of sniffing and tasting chemicals