1800s

Intro: The Beginning of Science 300- 400 B.C.: This was the first documented work of theories and principles of science being developed. At the beginning a philosopher by the name of Aristotle developed a theory that matter was made up of four elements: Fire, Water, Earth, and Air. However he was wrong but was considered a genius of his time period since this theory persisted as reality for 2000 years. After him another came by the name of Democritus. He considered that matter could not be divided and that it had to consist of small particles. He then began to recognize things to be made up of atoms as he called them from the greek word of atomos, which meant indivisible.

1800-1810: As the new era began a man named John Dalton began the age of scientific developments in what looks to be as one of the most influential years for science. As a young scholar in physics he began to experiment in many sciences using elements to understand properties of the earth. As the 1800s started he already developed a law that the total pressure of a mixture of gases amounted to the sum of the partial pressures that each individual gas exerted while occupying the same space. It soon became to be known as Dalton’s law of partial pressures. After he studied the results of colourblindness for a few years and was one of the first to conclude that it was usually genetic and was because of a lack of photoreceptors found in the eye, making people less sensitive to some colours. After he took his work further doing theoretical work. In later years he began the principles for the first atomic theory developed. He identified individual elements to hold particles and introduced atoms by weights and masses. He was one of the first to do so, and in this he was awarded nobel prizes as most of his theories were distinguished as fact. His atomic theory that he introduced had four main principles behind it which were:
1. All matter is made of atoms which are indestructible.
2. All atoms of a given element are identical in mass and properties.
3. Compounds are formed by two or more different kinds of atoms being mixed together. 4. A chemical reaction is a rearrangement of atoms.
These were later altered and changed as more discoveries happened. With the discoveries of these principles it allowed for compounds of atoms to be more easily maneuvered and allowed chemists to better understand the elements. With these discoveries he also began to introduce other laws such as law of conservation of mass and law of constant composition. His later work focused more on briefly outlining atomic models of elements based on experimentation and the laws.

The Beginning of the 20th century

1900- 1910: As the century began more significant developments happened in the first ten years than the rest of the following years. As names such as Joseph John Thomson, Neil Bohr, and Ernest Rutherford became some of the most famous in science history. The history of the atom was changing with more belief that it was not indivisible or was no longer a foreign entity but was an absolute fact of matter. J.J thompson was the first to get results from his experimental testing which consisted of using cathode rays and gas discharge in tubes to study how the atom recognized charges. As he watched the reactions he concluded that the atom was made up of both positive and negative charges. He then focused his research on the negatively charged entities that he believed orbited the atom. He later wrote about these anomalies and was credited with the first discovery of the electron. After this he concluded with other minds how to separate these molecules