Chemistry Reference
In-Depth Information
1234567
8
9
Atomic Structure
Lesson 3-1: Modern Atomic Theory and Model
The concept of “atoms” is believed to have originated in ancient Greece.
Democritus and his teacher Leppicutius were supporters of what has been
called a discontinuous theory of matter, which means that all matter is made
up of tiny particles, which are separated by spaces. They argued that if you
kept cutting a sample of a substance up into smaller and smaller pieces, you
would eventually get down to the smallest complete piece of that substance.
Democritus called this smallest particle atomos, which means indivisible.
This atomic theory didn't attract too many followers over the next 2,000
years or so. However, in the 1600s and 1700s, early chemists began publish-
ing the results of experiments that they were carrying out. Evangelista
Torricelli (1608-1647) experimented with air pressure. Robert Boyle (1627-
1691) discovered and published his gas law, which we will study in Chapter 8.
In 1661, Robert Boyle published The Sceptical Chymist, which argued the
virtues of an atomic theory.
Despite Robert Boyle's best efforts, the atomic theory did not become
widely accepted during his lifetime. Most scientists agree that the “birth”
of modern chemistry had to wait almost another 100 years after Boyle's
death, when Antoine Lavoisier (1743-1794) would publish his great work,
Traite Elementaire de Chimie, in 1789. Considered by many to be the founder
of modern chemistry, Lavoisier carried out carefully controlled experiments,
which provided real evidence for the Law of Conservation of Mass, which
we covered in Lesson 1
-
4.
John Dalton (1766-1844) summarized the works of Lavoisier and many
other early chemists in a “modern” atomic theory, which stated:
