Answers

2014-10-05T17:29:01+05:30
In 1862, Alexandre-Emile listed the elements on paper tape and wound them, spiral like, around a cylinder. In 1864, English chemist John Newlands noticed that, if the elements were arranged in order of atomic weight, there was a periodic similarity every 8 elements. In 1869, Lothar Meyer complied a periodic table of 56 elements based on a regular repeating pattern of physical properties such as molar volume. Also in 1869, Russian chemist Dmitri Mendeleev produced a periodic table based on atomic weights but arranged ‘periodically’In 1894, William Ramsay discovered the noble gases and realised that they represented a new group in the periodic table.In 1914, Henry Moseley determined the atomic number of each of the known elements. In 1940, Glenn Seaborg artificially produced heavy mass elements such as neptunium.
0