5.+Chemistry

HISTORY LEARNING CENTRES: CHEMISTRY a. A timeline of key events Dyes such as woad, indigo & Tyrian purple are used in linens, windows, etc Glass & ceramic pottery || Dalton's atomic theory proposed Bohr-Rutherford atomic theory proposed Periodic table invented Radioactivity discovered || b. A list of key people involved and their short biographies //Jabir ibn Hayyan (Geber)// Born to Arab parents in Iran, Geber was unlike other scientists of his day in his practical experience in his field, having worked in an apothecary. He pioneered techniques such as crystallization and distillation, originating the move from purely theoretical work to experimental investigation in alchemy. He was primarily influenced by Greek and Neo-Platonist works that had been translated into Arabic; a polymath and prolific writer, he wrote over 200 books, 80 of which were about chemistry. He was put under house arrest in the last years of his life, until his death in 815.
 * **Date** || **Event** ||
 * Pre-700s || Metals are discovered & used in pure form and as part of alloys, eg steel & bronze
 * 4th century BCE || Advent of **alchemy** in **Alexandria** based on Greek philosophy.
 * Empedocles**’ (490 BC – 430 BC) theory of four elements, later modified by Aristotle.
 * Aristotle**’s (384 BC – 322 BC) theory of five elements – earth, fire, air, water and aether that made up all things. This was the theory that persisted until the scientific revolution. ||
 * ~ 400 BCE || Earliest atomic theory that all things are made up of atoms by **Democritus** (circa 460 BC – circa 370 BC) ||
 * 300 || Christianity proclaimed as official religion of Roman Empire. Eradication of pagan philosophy. ||
 * 500 || Preserved Hellenistic writing translated to Syrian in Persia. ||
 * 640-720 || Age of Muslim conquests. Syrian texts translated to Arabic. ||
 * Late 700s || Arab alchemist **Jabir ibn Hayyan** introduced experimental investigation into alchemy. ||
 * Late 700s || Jabir isolates minerals & other acids for the first time & describes three types of substances that foreshadow later classifications such as metals, non-metals & volatile substances ||
 * ~900 || **Abu Bakr ibn Zakariyya al-Razi** (also known as **Rhazes**) writes alchemy text //Secret of Secrets// which describes various chemical apparatus. ||
 * ~900 || Rhazes perfects techniques of crystallization and distillation invented by Jabir ||
 * 11th century || Works of Arabic alchemists, notably works of Jabir and al-Razi translated into Latin. ||
 * ~1100 – 1200 || **Avicenna** writes several treatises against alchemy & transmutation, which are later translated into Latin ||
 * ~1300 || Alchemy begins to gain traction in Europe with the work of **Albertus Magnus**, focusing on the transmutation of lead into gold & the philosopher's stone ||
 * ~1610 || **Jan Baptist van Helmont** invents the term 'gas' & thus begins the era of **pneumatic chemistry**, which focuses on understanding the properties of gases. ||
 * ~1610 || van Helmont conducts one of the first rigorous scientific experiments, erroneously concluding that trees gain weight only through water ||
 * 1660 || **Robert Boyle** states that the volume of a gas varies inversely with pressure ||
 * 1661 || Boyle publishes //The Sceptical Chymist//, arguing that all matter is made of atoms in motion & emphasizing the importance of rigorous scientific experimentation ||
 * 1667 || **Johann Becher** proposes the **phlogiston theory**, hypothesizing an element known as phlogoiston that exists in all flammable substances & is released during combustion. ||
 * 1753 || **Mikhail Lomonosov** disproves Boyle's experiment showing that metals gained weight upon combustion, exposing a flaw in the phlogiston theory ||
 * 1756 || **Joseph Black** isolates carbon dioxide as a gas distinct from air; terms it “fixed air” ||
 * ~1760 || **Henry Cavendish** isolates & studies hydrogen (“inflammable air”), recognizing it for the first time as an element in itself ||
 * 1774 || **Joseph Priestly** isolates oxygen gas, which he believes to be a new kind of gas known as “dephlogisticated air” ||
 * 1780s || **Antoine Lavoisier** establishes consistent standards of usage for the chemical balance ||
 * 1783 || Lavoisier publishes //Réflexions sur le Phlogistique,// which shows that Priestly’s “dephlogisticated air” is actually oxygen, thus disproving the idea of air as an element & the phlogiston theory ||
 * 1785 || Cavendish describes the composition of the atmosphere to a great degree of accuracy ||
 * 1787 || Lavoisier publishes //Methods of Chemical Nomenclature//, creating a system of nomenclature still largely in use today ||
 * 1789 || Lavoisier publishes //Traité Élémentaire de Chimie//, which lays out a new set of underlying principles in chemistry including the **law of the conservation of mass**, which he proves through quantitative chemical experiments that anticipate later **stoichiometry**. ||
 * 1793 || The **French National Convention**, distrustful of the largely aristocratic scientific establishment, abolishes the Academy of Sciences ||
 * Post-1793 || Modern-day chemistry develops

//Roger Bacon// 1210-1292 Bacon was educated in the Aristotelian conception of the universe (//libri naturales//). However, around 1240 he began to study ancient authorities translated from Greek and Arabic that had extensive knowledge of the mathematical and experimental sciences. He went on to write widely on those subjects, including alchemy and practical chemistry, and was one of the first advocates of chemistry as a field alongside physics and biology, and a subject crucial to medicine. He is most widely known for his popularization of the inductive scientific method, or empiricism.

//Jan Baptist van Helmont// A Belgium chemist and physician, van Helmont was born in 1580. He was educated in the classics and dabbled in mystical philosophy, magic and medicine before settling on the field of chemistry. He was one of the first true chemists deviating from the alchemic tradition, and defined his field for the next half-century with his focus on the study of gases that became known as pneumatic chemistry. He is, in fact, credited with inventing the term ‘gas’. To van Helmont, knowledge was a divine gift from God and there was no one way to understand this creation. Nevertheless, he incurred the wrath of the Spanish inquisition for his supposed contradiction of established miracles, and was preventing from publishing his work for 3 years. His research was posthumously collected and published as //Ortus medicinae//.

//Robert Boyle// Boyle was born in 1627 to the Earl of Cork Richard Boyle; the substantial inheritance his ancestry provided him allowed him to devote himself with science without monetary concerns. He was a prominent member of the Invisible College, a term for the informal circles of scientists who frequently met and shared new research, and one of the founders of the Royal Society, while also a devout Christian. He did not believe his religion conflicted with his occupation, though he had to reject the presidency of the Royal Society due to religious reasons. In later years, his health declined rapidly, and he withdrew from public life until his death in 1691. His work built upon van Helmont and his focus on gases, formulating the eponymous law that the volume of a gas varies inversely with pressure (PV=C). In 1661, he published the influential //The Sceptical Chymist//, which argued that all matter is made of atoms in motion and emphasized the importance of rigorous scientific experimentation.

//Joseph Priestley// Priestley was born in 1733 and first established a career in theology and teaching, accepting a post at Warrington Academy in 1761. The intellectual environment there stimulated an interest in natural philosophy, and he subsequently published a history of the study of electricity that became the accepted canon for over a century. His later work concerned chemistry; a lifelong defender of the phlogiston theory, he wrote the six-volume //Experiments and Observations on Different Kinds of Air// that elucidated his version of the theory while rejecting Aristotle’s four-element model. Ironically, his isolation of oxygen gas in 1774 (which he termed "dephlogisticated air") eventually led, through Lavoisier, to the discrediting of the phlogiston theory.

//Antoine-Laurent de Lavoisier// Lavoisier was born in Paris on August 26, 1743. Trained in law, he turned instead to scientific work, publishing papers on agriculture and a plan to improve street lighting in Paris. His inherited wealth allowed him to maintain an impressive laboratory that became a gathering place for other scientists. He was elected to the Royal Academy of Science in 1768, but his most influential work was published in the 1780s, when he disproved the phlogiston theory of chemistry based on Joseph Priestley’s isolation of what Lavoisier recognized as oxygen and not simply another form of air and went on to found a new system of scientific nomenclature and propose a new set of principles for the study of chemistry. Lavoisier was active in pushing social reforms under the monarchy and sympathized with the revolutionary cause; however, when the Reign of Terror began in September 1793, his previous position as the director of a firm collecting taxes for the crown made him a target instead, and he was guillotined on May 8, 1794.

c. Major milestones in the history of chemistry Early alchemists in the city of Alexandria fused Greek philosophy with Egyptian knowledge of metals and elements into alchemy, which focused on transmuting base metals into gold and the search for the ‘elixir of life’, or the philosopher’s stone. Based on Aristotle’s belief that all things are made of five elements, alchemists believed that by adding or removing certain elements, base metals like lead could be transmuted into gold. Alchemists such as Geber introduced techniques such as distillation and crystallization and precursors of modern day lab apparatus were also invented. Many of the substances now involved in inorganic chemistry were also identified and used in early alchemy, such as ethanol and mercury. Geber discovered how to make sulphuric acid, and by distilling it with other salts, produced hydrochloric acid and nitric acid.
 * i. Advent of Alchemy – Gold and the Elixir of Life**

Pneumatic chemistry is the study of gases most commonly associated with the seventeenth and eighteenth century studies. Its founder was Jan Baptist van Helmont, who coined the term ‘gas’ and began conducting experiments focusing on gases, particularly the relationship between chemical reactions and the properties of gases and what matter was made of. Many gases such as carbon dioxide, hydrogen and nitrogen were isolated for the first time during this time when pneumatic chemistry dominated the field. Robert Boyle also contributed to pneumatic chemistry with Boyle’s law, which described the inversely proportional relationship between pressure and volume of gases.
 * ii. Pneumatic Chemistry**

In 1661 Boyle published the Sceptical Chymist which criticised the Aristotelian view of the universe. Although he did not describe elements the way they are understood today, he believed that matter consisted at root of “primitive and simple, or perfectly unmingled bodies” which could combine with other elements to form an infinite number of compounds. This was an extension of his support for early atomic theory involving what he described as tiny “corpuscles” and was important in promoting an area of thought which would influence groundbreaking work by Antoine Lavoisier and Joseph Priestly. In this book, Boyle also established chemistry as a separate science distinct from medicine, biology and alchemy.
 * iii. The Sceptical Chymist**

Antoine Lavoisier discovered that while the overall weight of the vessel remained the same during combustion (the conservation of matter), the solids being heated could gain mass. He then concluded that the weight gain of the solid had been caused by some kind of combination with the air trapped in the container. This idea was further developed when he met Joseph Priestly and the latter explained his discovery of dephlogisticated air which was in line with the theory that all flammable substances contained a substance called “phlogiston” which was central to combustion and released during it. Through experiments, Lavoisier disproved the phlogiston theory by 1778 by showing that not only was Priestly’s ‘dephlogisticated air’ the gas which was combining with matter but moreover it was essential for combustion. He published //Traité Élémentaire de Chimie// in 1789, outlining a new unified theory of chemistry and thus heralding the end of the phlogiston theory and the beginning of modern chemistry. His experiment was the first quantitative chemical experiment, an early form of stoichiometry – the relationship between the measurable (such as mass) aspects of reactants and its products of a chemical reaction, which adheres to Lavoisier’s the law of conservation of mass (the mass of a closed system remains constant over time).
 * iv. Phlogiston theory** **& the** **Law of Conservation of Mass**

d. Why were these discoveries and achievements important and/or significant? In the process of questing for gold, many chemical processes were invented that later formed the basics of modern inorganic chemistry such as distillation and crystallization, along with the equipment needed for such experiments, for example -Alembic (type of distillation apparatus) -Furnaces & crucibles -Refrigerated coil -Sieves -Filters Many of the substances now involved in inorganic chemistry were also identified and used in early alchemy, such as sulphuric acid. Sulphuric acid is the most important mineral acid in chemistry experimentation as all other acids can be produced by a combination of sulphuric acid and another substance. Nitric acid and hydrochloric acid are also important in the chemical industry. Knowledge of properties of these substances laid down the foundation of observation of properties of substances for chemistry as a science. It also formed the basis of the classification of various substances based on their observable properties. As such, alchemy was significant in forming the basis of approaches and techniques associated with chemistry.
 * i. Advent of Alchemy – Gold and the Elixir of Life**

Due to its emphasis on the study of gases, many components of air, such as oxygen and nitrogen, were isolated for the first time under pneumatic chemistry and its successor, the phlogiston theory. Pneumatic chemistry contributed greatly to the understanding and measurement of atomic and molecular masses and was also vital in the development of John Dalton’s atomic theory which eventually paved the way for the periodic table. ** Boyle anticipated later work by Dalton in formulating modern-day atomic theory by promoting the concept that all things are made of tiny "corpuscles" and “primitive and simple, or perfectly unmingled bodies” which could combine with other elements to form an infinite number of compounds. Dalton's theory stated later that 1) All matter is made of atoms ("corpuscles" according to Boyle) 2) All atoms are identical in mass and properties ("primitive... bodies") and 3) Compounds are formed by a combination of two or atoms of different elements.
 * ii. Pneumatic Chemistry
 * iii. The Sceptical Chymist**

Dalton's theory is the foundation of modern-day chemistry, although his theory has been improved upon. As one can see from above, Dalton's atomic theory is extremely similar to the ideas that Boyle promoted in the Sceptical Chymist, thus making the Sceptical Chymist an important milestone in the history of chemistry as Boyle was one of the first prominent chemists to advocate said theory and emphasize the importance of experimental rigor.

The disproving of the phlogiston theory paved the way for the rise of modern chemical theory, one that recognized oxygen and other gases as fundamental elements that were simultaneously components of air. Lavoisier's related work laid down fundamental principles for later work in the field in his articulation of the law of conservation of mass and stoichiometry. **
 * iv. Law of Conservation of Mass

References: JRank Science & Philosophy (2010). //Chemistry - Alchem////y in the Scientific Revolution//. Retrieved February 21, 2010, from http://science.jrank.org/pages/8580/Chemistry-Alchemy-in-Scientific-Revolution.html Larson, Philip G. (ed). //Antoine Laurent Lavoisier.// Retrieved February 21, 2010, from http://cti.itc.virginia.edu/~meg3c/classes/tcc313/200Rprojs/lavoisier2/home.html School of Mathematics and Statistics, University of St Andrews, Scotland (2000). //Robert Boyle.// Retrieved February 21, 2010, from http://www-history.mcs.st-andrews.ac.uk/Biographies/Boyle.html Chemical Heritage Foundation. //Jabir// //ibn Hayyan//. Retrieved February 21, 2010, from http://www.chemheritage.org/explore/ancients-hayyan.html Wolfram Research. //Lavoisier, Antoine.// Retrieved February 21, 2010, from http://scienceworld.wolfram.com/biography/Lavoisier.html Balchin, J. (2004). Robert Boyle, Antoine Lavoisier, John Dalton. (2004). // Quantum leaps 100 scientists who changed the world //. London, United Kingdom: Arcturus Publishing Limited. Lindberg, D., Bacon, R. (1996//). Roger Bacon and the origins of Perspectiva in the Middle Ages: a critical edition and English translation of Bacon's Perspectiva, with introduction and notes.// Oxford University Press. Kuhn, Thomas S. (1996). //The Structure of Scientific Revolutions// (3rd ed.). Chicago, IL: The University of Chicago Press. McNeill, Meaghan (2009). //Science Emergency Cram Kit// Sophy Lee, (Ed.) DemiDec Resources. Meidenbauer, J. (2004). Sulfuric acid: the alchemist's dream. (2004). // Discoveries and inventions from prehistoric to modern times //. Lisse, The Netherlands: Rebo International b.v. Morris, Richard. The Last Sorcerers. //The Path from Alchemy to the Periodic Table.// Washington DC, United States: Joseph Henry Press. Parsons, J. (2002). Chemistry. (2002). // Dk illustrated family encyclopedia //. New York, United States: DK Publishing. Unknown author (2009). //Science Resource Guide- Introduction to Chemistry//. United States Academic Decathlon. Unknown author (2009). //Science Research Guide- Introduction to Chemistry//. United States Academic Decathlon