History of Atomic Theory
TABLE OF CONTENTS NO | TITLE | PAGE | 01 | Introduction | 3 | 02 | Democritus | 4 | 03 | Plato and Aristotle | 6 | 04 | John Dalton | 7 | 05 | J.J. Tomson | 9 | 06 | Robert Millikan | 11 | 07 | E. Goldstein | 14 | 08 | James Chadwick | 16 | 09 | Ernest Rutherford | 18 | 10 | References | 21 |
INTRODUCTION
It is quite remarkable to know that the work of scientist hundreds years ago lies at the heart of our understanding of the structure of atom. New Zealand scientist Ernerst Rutherford was the first to show that the atom is the building block of all matter that consists of a positively charged nucleus surrounded by tiny negatively charged electrons. The extraordinary achievements of these scientists have been instrumental development of chemistry over the past century. Today, we take the existence of atoms for granted. We can explain many aspects of the structure of the atom and in fact, current technology allow us to “see” and even manipulate individual atoms. However, scientific evidence for the existence of atoms is relatively recent, and chemistry did not progress very far until that evidence was found.
Democritus Democritus ( 460 a.c.– 370 a.c.) was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the universe. His early deductions about the composition of the basic component of nature led him to believe in unseen and uncuttable particles , called atomos.
This Greek philosopher wondered how he could be sitting in one part of his house and detect that bread was baking elsewhere in the house. Could it be that small particles of the bread were breaking away from the loaf and traveling through the air into his nose? Noticing that wet clothing gradually got drier and lighter led to the explanation that small, invisible pieces of
INTRODUCTION
It is quite remarkable to know that the work of scientist hundreds years ago lies at the heart of our understanding of the structure of atom. New Zealand scientist Ernerst Rutherford was the first to show that the atom is the building block of all matter that consists of a positively charged nucleus surrounded by tiny negatively charged electrons. The extraordinary achievements of these scientists have been instrumental development of chemistry over the past century. Today, we take the existence of atoms for granted. We can explain many aspects of the structure of the atom and in fact, current technology allow us to “see” and even manipulate individual atoms. However, scientific evidence for the existence of atoms is relatively recent, and chemistry did not progress very far until that evidence was found.
Democritus Democritus ( 460 a.c.– 370 a.c.) was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the universe. His early deductions about the composition of the basic component of nature led him to believe in unseen and uncuttable particles , called atomos.
This Greek philosopher wondered how he could be sitting in one part of his house and detect that bread was baking elsewhere in the house. Could it be that small particles of the bread were breaking away from the loaf and traveling through the air into his nose? Noticing that wet clothing gradually got drier and lighter led to the explanation that small, invisible pieces of
References: Cathode Ray Experiment. Retrived October 1, 2012 from Martyn Shuttleworth, Explorable. website : http://www.experiment-resources.com/cathode-ray-experiment.html Chris Conoley, Phil Hills James E Brady, Fred Senese, William H Brown, Thomas Poon, John Olmsted III, Gregory M Williams. (2008). Chemistry. Chapter 1 : The Atom (pp. 6-7). Australia : John Wiley & Sons Australia, LTD. Julia Burdge. (2009). Chemistry. Chapter 2: Atoms, Molecules and Ion (pp. 34 – 40). McGraw-Hill Company. Marks S. Cracolice, Edward I. Peters. (2004). Introduction of Chemistry An Active Learning Approach. Chapter 5: Atoms Theory: The Nuclear Model of the Atom (pp. 114-119). Thomson Books/Cole. Millikan Oil Drop Experiment. Retrived October 10, 2012 from Anne Marie Helmenstine, About.com. Website: http://chemistry.about.com/od/electronicstructure/a/millikan-oil-drop-experiment.htm Paul Kelter, Michael Mosher, Andrew Scott The Nobel Prize in Physics 1935. Retrived October 14, 2012 from Nobleprize.org. Website: http://www.nobelprize.org/nobel_prizes/physics/laureates/1935/chadwick-bio.html