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Post date: Oct 19, 2011 10:52:36 AM
Read pages 67-76 in Modern Chemistry and complete the models of the atom worksheet.
This week we are focusing on the development of the modern atomic model. Our investigation will begin with the Greek philosopher Democritus (~400 B.C.) who proposed the concept of a fundamental particle which he called "atomos" meaning indivisible. Over the following 2000 years, Democritus' atomic model was discarded in favor of Aristotle's continuous model of matter, which stated that matter could be infinitely divided into smaller pieces. During these years, alchemists focused their studies of matter on the goal of changing cheap metals into gold, which they called transmutation. Despite the fact that this pseudoscience did not incorporate the scientific method, it did contribute greatly to the understanding of matter of the time. New elements were identified and characterized according to the physical and chemical properties. The next advancement came with the study of masses involved in a chemical reaction, John Dalton, a schoolteacher known for his meticulous laboratory techniques did a number of experiments which led him to three groundbreaking theories:
1. The Law of Conservation of Mass
2. The law of Definite Proportions
3. The law of Multiple Proportions.
To be continued...
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