Ancient Greek Philosophers and Atom Models PDF

LET’S TEST HOW GOOD LISTENER YOU ARE.  Lesson 2 Conceptual e v o l u t i o n o f atom and elements Introductio n About 2,500 years ago, early Greek philosophers believed the entire universe was a single, huge entity. In other words, "everything was one." They believed that al...

LET’S TEST HOW GOOD LISTENER YOU ARE.  Lesson 2 Conceptual e v o l u t i o n o f atom and elements Introductio n About 2,500 years ago, early Greek philosophers believed the entire universe was a single, huge entity. In other words, "everything was one." They believed that all objects, all matter, and all substances were connected as a single, unchangeable "thing. Atoms: i d e a s from the ancient Greeks Democritus o f Leucippus o f a b d e r a (460- m i l e t u s ( 500 370 Bce) bce) The Indivisible Atom  Democritus and Leucippus Greek scholars who believed that matter could be divided into tiny particles until such point whereit can no longer be divided anymore.  Summary of their early ideas on atom 1. All matter is made up of tiny, indivisible particles called atoms, which come from the Greek word ATOMOS meaning UNCUTTABLE. The atoms are indestructible, impenetrable, and unchangeable.  Summary of their early ideas on atom 2. The atoms make up the universe as they are continuously moving in a “void” that surrounds them, repelling each other when they collide, or combining into clusters.  Summary of their early ideas on atom 3. Atoms are completely solid which means that there is no void or empty space inside that will make them prone to disintegration or destruction.  Summary of their early ideas on atom 4.Atoms are homogeneous in nature. They have no internal structures. 5.Atoms come in different shapes and sizes. Anaxagoras o f Empedocles o f clazomenae (500— a c r a g a s (490—430 428 BCE) BCE) Arguments Against Atomism Anaximenes o f Heraclitus o f m i l e t u s (585- Ephesus (535- 528 Bce) 475 b c e ) Arguments Against Atomism Aristotle o f stagira (384-322 Bce) Arguments  Anaxagoras He propounded a physical theory of “everything-in-everything,” and claimed that everything in the universe is composed of small, indivisible particles called "nous" (which translates to "mind" or "intellect" in Greek).  Empedocles He proposed that matter in all universe was composed of the four fundamental elements: earth, water, air, and fire. He believed that these elements combined and separated through the actions of two opposing forces he called "love" (philia) and  Anaximenes He believed that air (a boundless, infinite substance that can be altered and transformed into various forms) is the fundamental substance from which all things in the universe originate and to which they ultimately return.  Heraclitus He believed that the primeval substance is fire and change is the only reality. He argued that permanence was an illusion and everything is in a state of constant flux.  Aristotle He believed that everything in the universe is made up of the four elements: air, fire, water, and earth. He stated that believing in atoms would mean putting restriction on the gods, who have the power to divide elements smaller than the atom. Elements: ideas f r o m the ancient Greeks  What are the primordial substances from which everything is made up of? Anaximenes - Thales - water air Heraclitus - Xenophanes - fire earth Empedocles proposed that all four – air, fire, water, and earth, are the primordial substances. He called them roots.  Element The word element came from the Greek word “στοιχεῖον” (stoicheion) which means smallest division. It was first used by Plato.  Platonic Solids A set of five geometric shapes of solids that are characterized by having equal faces, equal angles, and equal edge lengths. Aristotle described each element with two qualities. Air was wet and hot. Fire was hot and dry. Water was wet and cold. Earth was dry and cold. Aether was neither hot nor cold and was neither contributions o f the alchemists t o the s c i e n c e o f chemistry  Alchemy It was a speculative science with goals of finding the elixir of life and the philosopher’s stone, which could transform base metals into gold. It was a protoscientific tradition practiced in Asia, Egypt, and Europe.  Asian Alchemy Indian Alchemists: Isolation of metallic zinc, invention of steel, and use of flame to identify metals. Chinese Alchemists: Creation of gold, invention of gunpowder, creation of poisons such as mercuric sulfide.  Asian Alchemy Islamic Alchemists: Jabir Ibn Hayyan, was the first to mention silver nitrate and red oxide of mercury in his works. His writings also a handful of described laboratory — distillation, techniques crystallization, reduction,calcination, dissolution, and  Egyptian Alchemy Manufacturing of imitation gold and silver. Making dyes and artificial gemstones. Fabricating pearls.  European Alchemy Paracelsus: believed that the organs of the body worked alchemically. He proposed that the three essentials (tria prima) salt, mercury, and sulfur, should be balanced to maintain health. He also created laudanum, an opium tincture used as a painkiller. Discovery o f the s t r u c t u r e o f the atom and i t s s ubatomic particles  Solid Sphere Model It was the first atomic model and was developed by John Dalton in 1808 after experimenting with mixture of gases. An atom is a solid sphere that could not be divided into smaller particles. All atoms of one element are identical to each other but different  Plum Pudding Model It was developed by Joseph John Thomson in 1897 through cathode rays experiment. Suggested that atoms were composed of a positively charged matrix with embedded electrons. Thomson discovered the electron (corpuscle) in 1904.  Nuclear Model It was developed by Ernest Rutherford in 1911 through foil and alpha particles experiment. Suggested small, dense, positively that atoms had a charge nucleus attheir d Rutherford discovered center. the proton in 1919.  Planetary Model It was developed by Niels Bohr in 1913. Electrons orbited the nucleus at different distances and had different energies. The colour of the light depended on the energies of the orbits.  Planetary Model It was developed by Niels Bohr in 1913. Electrons orbited the nucleus at different distances and had different energies. The colour of the light depended on the energies of the orbits. Thank yo u For yo u r participation