Lecture 1: The Essence of Chemistry

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The History of Chemistry

Chemistry is the Science of Matter.

The history of chemistry represents a time span from ancient history to the present. By 1000 BC, civilizations used technologies that would eventually form the basis of the various branches of chemistry. Examples include the discovery of fire, extracting metals from ores, making pottery and glazes, fermenting beer and wine, extracting chemicals from plants for medicine and perfume, rendering fat into soap, making glass, and making alloys like bronze. Although those processes were very much chemistry, we did not understand the molecular interactions that underline those reactions.

The Medieval Era

Attempts to explain the nature of matter and its transformations manifested into alchemy, the protoscience of chemistry. Despite their failures, the concepts of observation and documentation would later be implemented in chemistry and other academic disciplines. So, what went wrong with alchemy?

1. There was no systematic naming scheme for new compounds.
2. The language was esoteric and vague to the point that the terminologies meant different things to different people.
3. There was also no agreed-upon scientific method for making experiments reproducible. Some alchemists include phases of the moon and timing of the tides as part of their methodologies.

The 17th-18th Centuries

In early 17th and 18th centuries, society gradually separated chemistry and alchemy due to increased skepticism from the public and efforts by scholars such as the Anglo-Irish chemist Robert Boyle. From then on, theories that are and will be familiar to us would be developed, debated, and matured. Here are some examples:

• Robert Boyle published The Sceptical Chymist in 1661, which advocated for a rigorous approach to experimentation among chemists. One key component in the publication called for a more “philosophical” focus on theories rather than commercially focused. Boyle also is best known for the inversely proportional relationship between the absolute pressure and volume of a gas in an isothermal (constant temperature) closed system.

• The Theory of Phlogiston is developed in 1702 by German chemist Georg Stahl, naming the substance believed to be released in the process of burning “phlogiston”. In 1754, Scottish chemist Joseph Black isolated carbon dioxide . In 1773, Swedish German chemist Carl Wilhelm Scheele discovered oxygen . The theory was later dismantled due to challenges raised by Antoine Lavoisier and newer chemists through experimentation.

• A branch of chemistry – electrochemistry – was founded by Italian physicist Alessandro Volta in the late 1700s and early 1800s through the construction of the first electrical battery. It was made from stacked pairs of alternating copper (or silver ) and zinc discs separated by cloth or cardboard soaked in brine connected by a wire.

• Another branch of chemistry – thermochemistry – was pioneered by French chemists Antoine Lavoisier and Pierre-Simon Laplace. They invented the first ice-calorimeter and used it in the winter of 1782-1783. The calorimeter was used to determine the heat involved in various chemical changes.

We will discuss thermochemistry and electrochemistry in future chapters in this course.

The 19th Century and Beyond

In the 19th century, chemists further expanded the discipline with new discoveries. A handful of chemists are listed below alongside their contributions.

• John Dalton (English, discoverer of Dalton’s law of partial pressures)
• Jön Jacob Berzelius (Swedish, introduced the classical system of chemical symbols)
• Joseph Louis Gay-Lussac (French, known for concluding that equal volumes of gases expand equally with the same increase in temperature)
• Amedeo Avogadro (Italian, postulated that, under controlled conditions of temperature and pressure, equal volumes of gases contain an equal number of molecules)
• Dmitri Mendeleev (Russian, organized the periodic table)
• Josiah Willard Gibbs (American, formulated the concept of thermodynamic equilibrium)
• Marie Skłodowska-Curie (Polish-born French, pioneered radioactive chemistry and laid the cornerstone of the nuclear age)
• Ernest Rutherford (New Zealander, discoverer of the nucleus and half-life)

We will learn more about their discoveries in future chapters in this course.

In the 20th century, more advanced theories were developed, with the invention of chromatography, discovery and development of the Planck constant, nuclear fission, the Bohr model, Lewis structures, quantum chemistry, molecular orbital theory, and molecular biology and biochemistry. Because of how advanced some theories are, we will not discuss them in this course. However, this course will serve as a basis for further academic pursuits.

Applications for Chemistry

Since chemistry studies the properties of and interactions between matter, the application of chemistry ranges from nanoscience technology to agriculture to medicine.

Subdisciplinary and Interdisciplinary Branches of Chemistry

Numerous subdisciplines and interdisciplinary branches include but are not limited to:

• Biochemistry – a highly interdisciplinary field covering medicinal chemistry, neurochemistry, molecular biology, forensics, plant science, genetics, etc.
• Inorganic chemistry – the study of properties and reactions of inorganic compounds such as metals and minerals.
• Materials science – the preparation, characterization, and understanding of solid-state components or devices with a useful or future function.
• Nuclear chemistry – the study of how subatomic particles come together and make nuclei.
• Organic chemistry – the study of structures, properties, compositions, mechanisms, and reactions of organic compounds.
• Physical chemistry – the study of the physical and fundamental basis of chemical systems and processes, including thermodynamics, kinetics, electrochemistry, statistical mechanics, spectroscopy, and even astrochemistry.

Those branches usually overlap and impact each other considerably. Each branch is connected with the rest.

Industrial and Commercial Impacts of Chemistry

Chemistry contributes heavily to industrial output, which includes:

• Polymers – plastics and human-made fibers, including polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polyester, nylon, and acrylics.
• Synthetic rubber, surfactants, dyes, pigments, turpentine, resins, explosives, and other rubber products.
• Inorganic chemicals – salt, chlorine, soda ash, nitric acid, phosphoric acid, sulfuric acid, hydrogen peroxide, etc.
• Fertilizers – phosphates, ammonia, potash chemicals.

A wide variety of consumer products are also impacted by chemistry:

• Hygiene products – soaps, detergents, and cosmetics.
• Pesticides, air fresheners, flavors and fragrances, printing inks, adhesives, etc.

Last but not least, chemistry, alongside other disciplines, contribute greatly to medicine in the form of pharmaceutical drugs. They include but are not limited to:

• Antipyretics – reducing fever.
• Analgesics – painkillers.
• Antimalarial drugs – treating malaria.
• Antibiotics – inhibiting germ growth.
• Antiseptics – preventing germ growth near burns, cuts, and wounds.
• Stimulants – increasing brain activity.
• Tranquilizers – decreasing brain activity.
• Statins – reducing mortality for cardiovascular diseases.

Organic chemistry is highly involved in the discovery of new medication. However, to learn organic chemistry, we need to establish a thorough understanding of concepts in general chemistry.

The Scientific Method

Below is a diagram demonstrating how the scientific method works. Observation and curiosity lead to the formation of a hypothesis. The hypothesis is then tested multiple times through experiments. Observations, calculations, and documentations are made. If the results are consistent with the hypothesis, then the hypothesis contributes to discovery. However, if results are not consistent, the hypothesis is rejected, and the cycle continues. When a lot of testing yields constant observations, said knowledge becomes law. When a lot of testing supports the hypothesis, the hypothesis becomes a theory.

One of the powers of the scientific method lies in the ability to reproduce the experiment. If the experiment documented in research papers can be reproduced and yield the same results, the formulated hypothesis is further strengthened. This rigorous, comprehensive, and well-substantiated method of research contributes greatly to academic progress, which leads to technological and medical advancements. However, because of the rigor presented by the scientific method, research is rarely neat and clean – a lot of reworking, revisiting, discussions, reading, learning, and reflecting are required. Yet, it is because of the rigor, academic discoveries and theories can be trusted.

Green Chemistry

Chemical reactions can be intriguing and exciting in theory. However, in practice, a lot of reactions require conditions (specific solvents, energy input such as heat, catalysts, etc.). It can lead to waste generation, and sometimes hazardous products and side-products can be generated as well. In the context of increasing attention to problems of chemical pollution and resource depletion, we will briefly introduce the principles of green chemistry and its applications.

The 12 Principles of Green Chemistry

The American Chemical Society (ACS) outlined a framework for making a greener chemical, process, or product. It consists of 12 principles.

Examples of Green Chemistry

We will discuss relevant applications of green chemistry more in-depth as we go on with the course. For now, here are some examples that have a significant impact on our lives.

• The synthesis of simvastatin – a statin medication used to treat high cholesterol levels – is optimized to generate less hazardous waste and decrease costs. The previous process used hazardous chemicals and released a large volume of toxic waste. The new process, invented by Professor Yi Tang of the University of California, uses an engineered enzyme and a low-cost feedstock. This new process greatly reduces hazard and waste, is cost-effective, and meets the needs of customers.
• Biodegradable plastics can potentially be produced by microorganisms. Scientists at NatureWorks discovered that microorganisms convert cornstarch into a resin that is just as strong as the rigid petroleum-based plastic currently used for containers such as water bottles and yogurt pots.