The History of Chemistry ~ ~ Fire Water Earth Air A Brief History of Chemistry In fourth century B.C., ancient Greeks proposed that matter consisted of
fundamental particles called atoms. Over the next two millennia, major advances in chemistry were achieved by alchemists. Their major goal was to convert certain elements into others by a process called transmutation. The Greeks In 400 B.C the Greeks tried to understand matter (chemicals) and broke them down into earth, wind, fire, and air.
Democritus and Leucippus Greek philosophers Greek Model To understand the very large, we must understand the very small. Democritus Greek philosopher Idea of democracy Idea of atomos Atomos = indivisible Atom is derived No experiments to support
Democrituss model of atom idea Continuous vs. discontinuous No protons, electrons, or neutron theory of matter Solid and INDESTRUCTABLE Democritus DEMOCRITUS (400 BC) First Atomic Hypothesis Atomos: Greek for uncuttable. Chop up a piece of matter until you reach the atomos. Properties of atoms: indestructible. changeable, however, into different forms. an infinite number of kinds so there are an infinite number of elements. hard substances have rough, prickly atoms that stick together.
liquids have round, smooth atoms that slide over one another. smell is caused by atoms interacting with the nose rough atoms hurt. sleep is caused by atoms escaping the brain. death too many escaped or didnt return. the heart is the center of anger. the brain is the center of thought. the liver is the seat of desire. Nothing exists but atoms and space, all else is opinion. Four Element Theory Plato was an atomist Thought all matter was composed of 4 elements:
Earth (cool, heavy) Water (wet) Fire (hot) Air (light) FIRE Hot AIR Dry MATTER Wet EARTH
Cold WATER Relation of the four elements and the four q Blend these elements in different proportions to get all substances Some Early Ideas on Matter Anaxagoras (Greek, born 500 B.C.) Suggested every substance had its own kind of seeds that clustered together to make the substance, much as our atoms cluster to make molecules. Empedocles
(Greek, born in Sicily, 490 B.C.) Suggested there were only four basic seeds earth, air, fire, and water. The elementary substances (atoms to us) combined in various ways to make everything. Democritus (Thracian, born 470 B.C.) Actually proposed the word atom (indivisible) because he believed that all matter consisted of such tiny units with voids between, an idea quite similar to our own beliefs. It was rejected by Aristotle and thus lost for 2000 years. Aristotle (Greek, born 384 B.C.) Added the idea of qualities heat, cold, dryness, moisture as basic elements which combined as shown in the diagram (previous page). Hot + dry made fire; hot + wet made air, and so on.
Alchemy After that chemistry was ruled by alchemy. They believed that that could take any cheap metals and turn them into gold. Alchemists were almost like magicians. elixirs, physical immortality Alchemy Alchemical symbols for
transmutation: changing one substance into another In ordinary chemistry, we cannot transmute elements. Contributions of alchemists: Information about elements - the elements mercury, sulfur, and antimony were discovered - properties of some elements Develop lab apparatus / procedures / experimental techniques - alchemists learned how to prepare acids
- developed several alloy - new glassware Early Ideas on Elements Robert Boyle stated... A substance was an element unless it could be broken down to two or more simpler substances. Air therefore could not be an element because it could be broken down in to many pure substances.
Robert Boyle Modern Chemistry Beginnings of modern chemistry were seen in the sixteenth and seventeenth centuries, where great advances were made in metallurgy, the extraction of metals from ores. In the seventeenth century, Boyle described the relationship between the pressure and volume of air and defined an element as a substance that cannot be broken down into two or more simpler substances by chemical means. Modern Chemistry
During the eighteenth century, Priestley discovered oxygen gas and the process of combustion where carbon-containing materials burn vigorously in an oxygen atmosphere. Priestley In the late eighteenth century, Lavoisier discovered respiration and wrote the first modern chemistry text. His most important contribution was the law of conservation of mass, which states that in any chemical reaction, the mass of the substances that react equals the mass of the products that are formed. He is known as the father of modern chemistry.
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