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Period: 460 BCE to 370 BCE
Democritus
Democritus was a Greek philosopher who lived between 470-380 B.C. He developed the concept of the 'atom', Greek for 'indivisible. Believed that everything in the universe was made up of atoms, which were microscopic and indestructible. As the atom he believed that atom was a microscopic molecule and couldn’t be cut . -
Period: 384 BCE to 322 BCE
Aristotle
He was the author of a philosophical and scientific system that became the framework and vehicle for both Christian Scholasticism and medieval Islamic philosophy. Aristotle was also a teacher and founded his own school in Athens, known as the Lyceum. Aristotle also taught and believed in the four basic elements of the earth, water, air, fire, and dirt. -
Period: 356 to 322
Alexander the Great
Greek philosophers became interested in the Egyptian religion. Greek views of how matter is made up of the four elements of nature were merged with Egyptian religion. And discovered and began to discover chemistry but alchemy. The word Alchemy came from the word Khemia, which means Egypt. -
Period: to
Benjamin Franklin
Philadelphia, Pennsylvania, U.S., American printer and publisher, author, inventor and scientist, and diplomat. One of the foremost of the Founding Fathers, Franklin helped draft the Declaration of Independence and was one of its signers, represented the United States. He made important contributions to science, especially in the understanding of electricity. -
Period: to
Anton Laurent de La Voisier
French chemist and leading figure in the 18th-century chemical revolution who developed an experimentally based theory of the chemical reactivity of oxygen and coauthored the modern system for naming chemical substances. Having also served as a leading financier and public administrator before the French Revolution.Discovered the Law of Conservation of Mass: By proving that the mass of a metal oxide = the mass of the metal plus oxygen when the metal oxide decomposes. -
Period: to
Joseph Proust
He was a French chemist. He is best known for his discovery of the law of constant composition. It’s the copper carbonate mix. “He did this by making artificial copper carbonate and comparing it to natural copper carbonate. With this he showed that each had the same proportion of weights between the three elements involved” Proust was the first scientist to think that chemical compounds are formed from definite proportions. -
Period: to
John Dalton
English meteorologist and chemist, a pioneer in the development of modern atomic theory. Atomic theory, ancient philosophical speculation that all things can be accounted for by innumerable combinations of hard, small, indivisible particles called atoms of various sizes but of the same basic material. -
Period: to
William Crookes
British chemist and physicist noted for his discovery of the element thallium and for his cathode-ray studies, fundamental in the development of atomic physics.Atomic physics, the scientific study of the structure of the atom, its energy states, and its interactions with other particles and with electric and magnetic fields. -
Period: to
Becquerel
French physicist who discovered radioactivity through his investigations of uranium and other substances. In 1903 he shared the Nobel Prize for Physics with Pierre and Marie Curie. Physical science, the systematic study of the inorganic world, as distinct from the study of the organic world, which is the province of biological science. -
Period: to
Sir John Joseph Thomson
English physicist who helped revolutionize the knowledge of atomic structure by his discovery of the electron 1897. He received the Nobel Prize for Physics in 1906 and was knighted in 1908. J.J. Thomson’s discovery of the negatively charged electron had raised theoretical problems for physicists as early as 1897, because atoms as a whole are electrically neutral. -
Period: to
Marie Curie
Polish-born French physicist, famous for her work on radioactivity and twice a winner of the Nobel Prize. With Henri Becquerel and her husband. Radioactivity, property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. It is, in essence, an attribute of individual atomic nuclei. -
Period: to
Millikan
American physicist honoured with the Nobel Prize for Physics in 1923 for his study of the elementary electronic charge and the photoelectric effect.Photoelectric effect, phenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation. -
Period: to
Ernest Rutherford
New Zealand-born British physicist considered the greatest experimentalist since Michael Faraday (1791–1867). Rutherford was the central figure in the study of radioactivity, and with his concept of the nuclear atom he led the exploration of nuclear physics.Radioactivity, property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. It is, in essence, an attribute of individual atomic nuclei. -
Period: to
James Chadwick
English physicist who received the Nobel Prize for Physics in 1935 for the discovery of the neutron. Neutron, neutral subatomic particle that is a constituent of every atomic nucleus except ordinary hydrogen. It has no electric charge marginally greater than that of the proton but nearly 1,839 times greater than that of the electron.