History of The Atom
For this project, we were divided into groups of about four or five. Each group was responsible for becoming experts on a specific scientist. All of which were somehow involved in the discovery of the atom. Once we were experts, we created a poster board within our groups and then gave a presentation to our peers. The posters were then arranged in order to create a timeline of the history of the atom.
About The Scientists...
1. Leucippus and Democritus
The first people to discover the atomic theory were the Greek philosophers Leucippus and Democritus. They were the first to theorize that the world was composed of tiny particles called atoms. These particles were invisible to the human eyeThe number of things in being atoms is infinitely great. Each one of them is indivisible.Between them is empty space.
2. Aristotle
Aristotle’s theory made a great generalization off all matter being made of the four elements: fire, water, earth, and air. He also believed that there were four qualities to these elements: dryness, hotness, coldness, and moistness. In the Aristotle model there were two forces, conflict and harmony. So, each of the elements move naturally in a line to their “proper place,” where it will be at rest.
3. John Dalton
John Dalton is considered the Father of Modern Atomic theory, his efforts gave us our first understanding of the atom. His atomic theory, stated that elements consisted of tiny particles called atoms. Dalton said that the reason an element is pure is because all atoms of an element were identical and that in particular they had the same mass.
4. JJ Thomson
JJ Thomson discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube. Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. His development of the mathematical theory of electricity and magnetism, led him to a means of separating atoms and molecules according to their atomic weights. His work with Aston gave evidence of the existence of isotopes of neon.
5. Ernest Rutherford
His atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. The Rutherford model of the atom was simplified in a well known symbol showing electrons circling around the nucleus like planets orbiting the sun.
6. Niels Bohr
Bohrs model said the electron orbits the nucleus at a definite distance, electrons can only occupy certain orbits or shells in an atom. Each orbit represents a definite energy for the electrons in it.