Content deleted Content added
m Reverted edit by 205.164.153.142 (talk) to last version by Kurzon |
No edit summary Tags: Mobile edit Mobile web edit Advanced mobile edit |
||
Line 29:
In a paper titled ''Cathode Rays'',{{sfn|Thomson|1897}} Thomson demonstrated that [[cathode rays]] are not light but made of negatively charged particles which he called ''corpuscles''. He observed that cathode rays can be deflected by electric and magnetic fields, which does not happen with light rays. In a few paragraphs near the end of this long paper Thomson discusses the possibility that atoms were made of these ''corpuscles'', calling them ''primordial atoms''. Thomson believed that the intense electric field around the cathode caused the surrounding gas molecules to split up into their component ''corpuscles'', thereby generating cathode rays. Thomson thus showed evidence that atoms were divisible, though he did not attempt to describe their structure at this point.
Thomson notes that he was not the first scientist to propose that atoms are divisible, making reference to [[William Prout]] who in 1815 found that the atomic weights of various elements were multiples of hydrogen's atomic weight and hypothesised that all atoms were made of hydrogen atoms fused together.<ref name=Kragh2010>Helge Kragh (Oct. 2010). [https://css.au.dk/fileadmin/reposs/reposs-010.pdf Before Bohr: Theories of atomic structure 1850-1913]. RePoSS: Research Publications on Science Studies 10. Aarhus: Centre for Science Studies, University of Aarhus.</ref> Prout's hypothesis was dismissed by chemists when by the 1830s it was found that some elements seemed to have a non-integer atomic weight—e.g. [[chlorine]] has an atomic weight of about 35.45. But the
A few months after Thomson's paper appeared, [[George Francis FitzGerald|George FitzGerald]] suggested that the corpuscle identified by Thomson from cathode rays and proposed as parts of an atom was a "free electron", as described by physicist [[Joseph Larmor]] and [[Hendrik Lorentz]]. While Thomson did not adopt the terminology, the connection convinced other scientists that cathode rays were particles, an important step in their eventual acceptance of an atomic model based on sub-atomic particles.<ref>{{Cite journal |last=Falconer |first=Isobel |date=July 1987 |title=Corpuscles, Electrons and Cathode Rays: J.J. Thomson and the 'Discovery of the Electron' |url=https://www.cambridge.org/core/product/identifier/S0007087400023955/type/journal_article |journal=The British Journal for the History of Science |language=en |volume=20 |issue=3 |pages=241–276 |doi=10.1017/S0007087400023955 |issn=0007-0874}}</ref>
| |||