science assignment By rebecca.roach 330 Aristotle The four element theory was proposed by Aristotle: Earth, Air, Fire and water. 440 democritus and Leucippus The idea of the atom where by the democritus and leucippus which is a indivisible particle that all matter is made of. Jan 1, 1766 Henry Cavendish Hydrogen was discovered as a colorless, odourless gas by Henry Cavendish. Jan 1, 1778 Antoine Lavoisier The first extensive list of elements was made by Antoine Lavoisier with 33 elements which was made up with metals and non-metals Jan 1, 1864 Lothar Meyer An early version of a periodic table which was made up with 28 element by Lothar Meyer. Jan 1, 1864 Dmitri Mendeleev Dmitri Mendeleev produced a table with 66 known element in it. It was organized by atomic weight. Jan 1, 1894 William Ramsay Noble gases was discovered by William Ramsay. Jan 1, 1913 Henry Moseley The atomic number of every element was made by Henry Moseley.