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Democritus theorized the concept of atoms making up all matter. -
Aristotle proposed that everything was made from the four elements fire, earth, wind, and water. -
The experiments of alchemists contributed to glassmaking, metalworking, and ceramics. Their work led to the foundation for the first periodic table of elements. -
Robert Boyle created Boyle's laws which say that the volume of gas decreases with increasing pressure. His results implied that gasses are made of particles. -
The American's rebelled against the British. -
John Dalton came up with the atomic theory which states that elements consist of indivisible particles, all atoms of the same element are identical, and atoms can neither be created or destroyed. -
The northern Union fought against the southern Confederates. -
Dmitri Mendeleev created the first periodic table. -
J.J. Thomson performed the cathode ray experiment which showed the existence of electrons. Through this experiment he developed the plum pudding model. -
Hans Geiger discovered alpha and beta particles. He worked with Rutherford on the gold foil experiments and developed the Geiger counter to measure alpha particles. -
Robert Millikan determined the charge of the electron with the oil drop experiment. -
Ernest Rutherford discovered the atomic nucleus via the gold foil experiment. -
Niels Bohr proposed a model in which electrons travel in separate orbits around the nucleus. -
The first global world war. -
James Chadwick performed an experiment in which he bombarded beryllium with alpha particles. Through this he discovered neutrons. -
The second global world war was fought between the allies and the axis powers. -
America dropped the first nuclear bomb on Japan.