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500 BCE
Alchemist
developed a theory that all metals are composed of mercury and sulfur and that it is possible to change base metals into gold -
5 BCE
Leucippus and Democritus
In the 5th century BCE, Leucippus, also known as 'the Laughing Philosopher' as he was often cheerful while at work, and his pupil Democritus proposed that all matter was composed of small indivisible particles called atoms. Floating in a vacuum, which Democritus called the "void". Democritus was born around 460 BCE in Abdera, Thrace. -
Period: to
Antoine Lavoisier
born August 26, 1743, Paris, France and died May 8, 1794. He studied in the University of Paris. Lavoisier is for finding that mass is conserved in a chemical reaction. Giving us the understanding of why matter is conserved, atoms are neither created nor destroyed in a chemical reaction. -
Charles-Augustin de Coulomb
Charles-Augustin de Coulomb was born June 14, 1736, Angoulême, France and died August 23, 1806, Paris. After nine years in the Indies as a military engineer, he returned to France with impaired health. After the start of the French Revolution, he retired to a small estate at Blois, devoting himself to scientific research. -
Charles-Augustin de Coulomb
He is best known for the formulation of Coulomb’s law, which states that the force between two electrical charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. -
John Dalton
born September 5 or 6, 1766, and died July 27, 1844, Manchester. John Dalton was a Quaker. He started teaching at a local school when he was twelve, and later worked as a teacher at the New College in Manchester. Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties. It states that all matter is made of atoms, which are indivisible. And that all atoms of a given element are identical in mass and properties. -
William Crookes
Born June 17, 1832, London, and died April 4, 1919. He is credited with discovering the element thallium with the help of spectroscopy. He was also the first to describe the spectrum of terrestrial helium, in 1865. Crookes' is responsible for reconstructing the Cathode Ray, and showing that there is a negative charge in atoms -
J.J. Thomson
A physicists who is credited with the discovery of the electron, using the Cathode Ray tube. He was also able to predict the mass of this charge. Realizing that it is 1000 times lighter then that of a hydrogen atom. His theory suggests that each atom is a sphere filled with positively charged fluids. Corpuscles, the "electrons", the negatively charged particles floating in the fluid. -
Ernest Rutherfor
He was not convinced with Thomson's theory, so he did his own experiment. In his experiment, he fired alpha particles at a gold foil, and measured the particles as the we deflected. Because most of the particles were not reflected, he believed that there was a positive center called the nucleus. The nucleus is the densest part, and the electrons orbit the nucleus. So Rutherford stated that its like a mini solar system. -
Neil Bohr
Neil Bohr was an amazing student, but an average student. And during his experiments, he often set off explosions in his university. He agreed with the planetary version of Rutherford. His theory suggested that the electrons orbit the nucleus with a set size. The lower the energy of the electron, the lower the orbit. If one energy level is filled, a new level begins. When one electron moves from one level to another, this is called radiation. -
Erwin Schrödinger
Schrodinger was awarded the Nobel Prize for physics in 1933 for his work on what is known as the Schrodinger equation, and later Two prestigious awards were named after him several years before his death. He theorized that an electron does not travel in an exact orbit. We can only predict where its going, or should be. Not its exact location. The type of orbit, depends on its energy levels. -
James Chadwick
Chadwick was alive during the first world war. He was a Prisoner Of War during WWI because he was studying with scientists in Berlin, Germany. He was Knighted by the Crown of England in 1945, making him Sir James Chadwick. He also worked with the US government on the secretive Manhattan Project. He also discovered what was the neutron. He often focused his research on radioactivity.
