photo.jpg

## Dalton's Atomic Theory and the Modern Atomic Theory **Exercise 1.1** 1. List the postulates of Dalton's that continue to have significance (are retained in the modern atomic theory). 2. How does the atomic theory account for the fact that when 1.00 g of water is decomposed into its elements, 0....

## Dalton's Atomic Theory and the Modern Atomic Theory **Exercise 1.1** 1. List the postulates of Dalton's that continue to have significance (are retained in the modern atomic theory). 2. How does the atomic theory account for the fact that when 1.00 g of water is decomposed into its elements, 0.112 g of hydrogen and 0.888 g of oxygen are obtained regardless of the source of the water? **1.2.2 Postulates of Modern Atomic Theory** **Activity 1.4** Remember what you have learned in Grade 9 and discuss the following questions in a group of three or four, then present your responses to the whole class. 1. Which of Dalton's postulates about atoms are inconsistent with later observations? Do these inconsistencies mean that Dalton was wrong? 2. Is Dalton's model still useful? Most of the experiments conducted during the development of the modern atomic theory will be discussed in Sections 1.3-1.6. In this section, generalizations derived from the experiments are presented as postulates of the modern atomic theory. The modern atomic theory is generally said to begin with **John Dalton**. Dalton's work was mainly about the chemistry of atoms how they combine to form new compounds rather than about the internal structure of atoms. The modern theories about the physical structure of atoms did not begin until **J.J. Thomson** discovered the electron in 1897.