Periodic Table History Essay Outlines
In 1680 Robert Boyle also discovered phosphorus, and it became public.
In 1809 at least 47 elements were discovered, and scientists began to see patterns in the characteristics.
In 1863 English chemist John Newlands divided the then discovered 56 elements into 11 groups, based on characteristics.
In 1869 Russian chemist Dimitri Mendeleev started the development of the periodic table, arranging chemical elements by atomic mass. He predicted the discovery of other elements, and left spaces open in his periodic table for them.
In 1886 French physicist Antoine Bequerel first discovered radioactivity. Thomson student from New Zealand Ernest Rutherford named three types of radiation; alpha, beta and gamma rays. Marie and Pierre Curie started working on the radiation of uranium and thorium, and subsequently discovered radium and polonium. They discovered that beta particles were negatively charged.
In 1894 Sir William Ramsay and Lord Rayleigh discovered the noble gases, which were added to the periodic table as group 0.
In 1897 English physicist J. J. Thomson first discovered electrons; small negatively charged particles in an atom. John Townsend and Robert Millikan determined their exact charge and mass.
In 1900 Bequerel discovered that electrons and beta particles as identified by the Curies are the same thing.
In 1903Rutherford announced that radioactivity is caused by the breakdown of atoms.
In 1911 Rutherford and German physicist Hans Geiger discovered that electrons orbit the nucleus of an atom.
In 1913 Bohr discovered that electrons move around a nucleus in discrete energy called orbitals. Radiation is emitted during movement from one orbital to another.
In 1914 Rutherford first identified protons in the atomic nucleus. He also transmutated a nitrogen atom into an oxygen atom for the first time. English physicist Henry Moseley provided atomic numbers, based on the number of electrons in an atom, rather than based on atomic mass.
In 1932 James Chadwick first discovered neutrons, and isotopes were identified. This was the complete basis for the periodic table. In that same year Englishman Cockroft and the Irishman Walton first split an atom by bombarding lithium in a particle accelerator, changing it to two helium nuclei.
In 1945Glenn Seaborg identified lanthanides and actinides (atomic number >92), which are usually placed below the periodic table.
The periodic table of elements, organized thoughtfully from hydrogen to ununoctium, is a tribute to the accomplishments of modern chemistry and physics. Since Dmitri Mendeleev developed an early version of the now-ubiquitous layout in 1869, discovering a new element has been a surefire way for a scientist to grab a place in the history books--and in the pages of Popular Science.
See the gallery.
Showing just how fundamental the elements are to modern science, the third-ever issue of PopSci, from August 1872, included a lengthy essay outlining the history of the "different sorts of matter," predicting correctly that scientists might continue discovering elements for "centuries to come."
But it hasn't all been fame and glory. PopSci announced in 1926 that the first American had identified a new element, only to declare later that "illinium" was a fake. Oh, and there was that time in 1931 when we proudly reported that scientists could pack up and go home: all the elements had been found!
Check out this week's archive gallery for more super-nerdy chemistry drama.