Development of the Atomic Theory

Lesson Title: Contributions of early Scientiest in the development of the Atomic Theory

Learning Outcome:
At the end of the sessions, you must be able to:
1. Trace the beginning of the development of the atomic theory.
2. Identify and recognize the significance of the contributions of early scientists in the development of atomic theory.

Learning Presentation
The atom is the most basic building block of matter, and chemistry is defined as the study of matter. Therefore to fully understand chemistry we must take a look at the atom.
What is an atom and what does it looks like?
I want you to imagine an atom and we will compare it later if your idea fits with the existing model of an atom.

Atoms though it may seem as a current idea was developed long ago. By Leucippus of Miletus and his student Democritus of Abdera.

Leucippus and Democritus: How did the two philosophers characterize the smallest unit of matter? What does the Greek word atomos mean?

Click on here to know how they came up with the idea of atoms


Another scientist gave evidence to support Democritus idea about atoms?
click here



John Dalton (1766-1844), an English chemist, integrated the results of the work of Boyle, Lavoisier and Proust and used them to provide the theory about the atomic nature of all matter. He was credited for the atomic theory. Why was the credit for atomic theory not given to Leucippus and Democritus when they were the first people to express the idea?

How significant were the studies of Boyle, Lavoisier and Proust in the development of atomic theory?


Generalization:
1. The idea of atoms as the smallest particle of matter started with Leucippus and Democritus about 400 BC.

2. In his study on gases, Robert Boyle (1627-1691) explained compressibility of air in terms of tiny particles forced closer together.

3. The Law of Conservation of Mass proposed by Antoine Lavoisier (1743-179) could be explained by atoms being indivisible. In chemical reactions, atoms only separate and/or unite with other atoms. No atoms can be destroyed nor created; thus, no change in weight of products is expected.

4. The Law of Definite Proportions or the Law of Definite Composition proposed by Joseph Louis Proust (1754-1826) could be explained using the idea of atoms. A compound is formed by the union of definite number ratio of combining atoms.

5. The Law of Multiple Proportions was put forward by John Dalton.

6. The three laws served to support the atomic theory proposed by Dalton in 1804. Without the work of these three scientists, Democritus idea of atoms could not have turned into a theory.

Assignment:
Visit my furom and give me a summary of the scientist that contributed to the atomic theory, also include the significance of wach discovery plus a summary of who do you think contributed the most to the atomic theory and why? click here to post answer

Evaluation:
Test your skill by clicking here, a score of more than of 70% is considered excellent

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