Chemistry is a branch of science that has existed for a long time. Chemistry dates back to prehistoric times. Chemistry has been around so long that scientists have classified it into 4 general chronological categories. These four categories are prehistory, early Christian era, late 17th century (alchemy), traditional chemistry and modern chemistry. Some of the very first recorded chemists where men like Democritus and Aristole. These men lived during the British Columbia era and have a great influence on the way we practice modern chemistry today. Starting with Democritus, the man who claimed that the atom was the simplest unit of matter. Democritus of ancient Greece asked the question: Could matter be divided into smaller and smaller pieces forever or was there a limit to the number of times a piece of matter could be divided? Democritus had a theory that it would eventually become too small to cut. This room could no longer be divided. He named this indivisible matter atomos. For Democritus of Greece, atoms were small, hard particles, all made of the same material, but of different shapes and sizes. He said they were always on the move and able to be reunited. Ancient Greek Aristotle added to the theory by declaring the existence of our only four elements: fire, air, water and earth. All matter is made up of one of these four elements and matter is made up of these four elements and matter had four properties: hot, cold, dry and wet. Aristotle was born in Stagira in northern Greece, the son of Nichomachus, a court physician to the Macedonian royal family. He initially studied medicine, but was later sent to Athens and became a philosopher under a man named Plato. Alchemy is what became the...... middle of paper...... each charge had a mass ratio of 1.759E8 coulombs. per gram. He concluded that all atoms had this negative charge (through further experiments) and he renamed cathode rays electrons. His model of the atom showed a sphere of positively charged material with negative electrons trapped within it. Thomson received the Nobel Prize in Physics in 1906. James Chadwick discovered the neutron. Enrico Fermi bombards elements with neutrons and produces elements of the highest atomic number. Nuclear fission occurred when Fermi bombarded uranium with neutrons. He received the Nobel Prize in Physics in 1938. Albert Einstein probably also made the greatest contribution to chemistry. He was part of a group of scientists who embarked on a mission to create an atomic fission reaction. It was known as the Manhattan Project and created the greatest chemical invention ever: the atomic bomb..