Chemistry and Society

ChemistryandSociety History of Chemistry Fall 2011 Dr. Victor Vilchiz

Alchemy Is in essence the ancestor of modern chemistry Alchemy was more than a science It was a philosophy A way of life Alchemists strived to reach pureness and perfection. Alchemists venerated gold as the symbol of perfection

Alchemy It was believed that to posses gold will make you rich and pure To drink gold meant to live forever Alchemy became the movement to find a way to transform (transmute) matter into gold. While these believes may seem silly and/or far-fetched they were widely accepted.

The search for the elixir of life It was known that it was possible to take iron and make steel and that if you mixed copper and zinc you will get brass. Why wouldn’t be possible to make gold? Needless to say the search for the elixir was futile and eventually alchemy gave way to new scientific questions and approaches.

Alchemy’s Legacy While it might be true that alchemy failed to produce an answer to its driving force it was not by any means a waste. Many process we now use were discovered or developed during the alchemists years. Distillation Fermentation Putrefaction Many elements were also discovered Bi, Zn, As, Co, and P

Alchemy to Chemistry Where does Chemistry come from? We are not 100% sure where the name comes from but there are several possibilities It could had come from Egypt Khem = turn black It could had come from GreeceCheo=to cast It could had come from ChinaChin-I=gold making juice.

Where to now? So making gold was not possible… now what? The obvious question will be then… why can’t we make gold? The quest to understand what was going on began and thus modern chemistry was born.

Ancient to Modern In the ancient times of alchemy we had only “AFEW” Elements. Air Fire Earth Water Currently we know 116 elements of which only 111 are recognized by the IUPAC.

The study of AIR Gold was replaced by air as the primary study subject. It is abundant and it behaves differently under different circumstances. It was pointed out that at times when air came in contact with lime water it will produced a cloudy solution. This air was baptized as “Fixed Air” We now know it as CO2 (carbon dioxide).

Types of AIR There were other times when air led to fiery explosions. This type of air is referred to as “explosive” air It is now known as Hydrogen Air at times produce very noxious odors. Thus, it was referred to as “noxious air” This one is now known as Nitrogen We are missing one type of air that is very important.

Where did the OO go? Oxygen was discovered while experiments with mercury (I) oxide were performed. As HgO is heated a separation of the elements takes place resulting in liquid mercury and gaseous oxygen. As the experiment was concluded a smoldering piece of wood burst into flames, hence Oxygen was known as “flammable air,” as the just heated HgO sample was placed close by.

ChemistryandSociety Matter Fall 2011 Dr. Victor Vilchiz

Matter • There are two principal ways of classifying matter: • By its physical state as a solid, liquid, or gas. • By its chemical constitution as an element, compound, or mixture.

Solids, Liquids, and Gases • Solid: Atoms or molecules have a fixed shape. They can be reshape, malleability, can be made into wires, ductile. They are relatively incompressible, fixed volume. (solid example) • Liquid: Atoms or molecules have some freedom to move around and liquid has a fixed volume but no fixed shape. Liquids are slightly compressible. (liquid example) • Gas: Molecules or atoms have freedom to move. Conforms to container shape but it is not volume restricted.(gas example)

Molecularrepresentation of a solid. In a solid each molecule is close to its neighbors and restricted to vibrating back and forth around a specific location. Return to Lecture

Molecular representation of a liquid. In a liquid the molecules are close together, but they can move past each other; each molecule can move a short distance before bumping into one of its neighbors. Return to Lecture

Molecular representation of a gas. In a gas the molecules are much farther apart than in liquids or solids, and they move relatively long distances before colliding with other molecules. Return to Lecture

Elements, Compounds, and Mixtures • Millions of substances have been characterized by chemists. Of these, a very small number are known as elements, from which all other substances are made. • An element is a substance that cannot be decomposed by any chemical reaction into simpler substances. (examples) • The smallest unit of an element is the atom.

Elements: mercury, arsenic, sulfur, iodine, magnesium, bismuth. Photo courtesy of American Color. Return to lecture.

Chemistry and Society