Editing Ernest Rutherford (section)

=== Model of the atom ===
{{See also|Rutherford–Bohr model| Rutherford scattering}}
[[File:Gold foil experiment conclusions.svg|right|thumb|''Top:'' Expected results: [[alpha particle]]s passing through the [[plum pudding model]] of the atom undisturbed.<br />
''Bottom:'' Observed results: a small portion of the particles were deflected, indicating [[Atomic nucleus|a small, concentrated charge]]. Diagram is not to scale; in reality the nucleus is vastly smaller than the electron shell.]]

Rutherford continued to make ground-breaking discoveries long after receiving the Nobel prize in 1908.<ref name=PaisInwardBound/>{{rp|63|q=...Rutherford, who rose to his greatest heights after 1908, most notably because of his discovery of the atomic nucleus}} Under his direction in 1909, [[Hans Geiger]] and [[Ernest Marsden]] performed the [[Geiger–Marsden experiment]], which demonstrated the nuclear nature of atoms by measuring the deflection of [[alpha particles]] passing through a thin gold foil.<ref>{{cite web |last1=Pestka |first1=Jessica |title=About Rutherford's Gold Foil Experiment |url=https://sciencing.com/rutherfords-gold-foil-experiment-4569065.html |website=Sciencing |access-date=27 June 2023 |language=en |date=25 April 2017 |archive-date=27 June 2023 |archive-url=https://web.archive.org/web/20230627004502/https://sciencing.com/rutherfords-gold-foil-experiment-4569065.html |url-status=live }}</ref> Rutherford was inspired to ask Geiger and Marsden in this experiment to look for alpha particles with very high deflection angles, which was not expected according to any theory of matter at that time.<ref>{{cite book |last1=Dragovich |first1=Branko |title=Ernest Rutherford and the Discovery of the Atomic Nucleus |publisher=Institute of Physics |location=Belgrade |url=http://bsw2011.seenet-mtp.info/pub/bss2011-DragovichB-abs.pdf |access-date=27 June 2023 |archive-date=27 June 2023 |archive-url=https://web.archive.org/web/20230627004502/http://bsw2011.seenet-mtp.info/pub/bss2011-DragovichB-abs.pdf |url-status=live }}</ref><ref>{{cite journal |last1=Davidson |first1=Michael W. |title=Pioneers in Optics: Johann Wilhelm Ritter and Ernest Rutherford |journal=Microscopy Today |date=March 2014 |volume=22 |issue=2 |pages=48–51 |doi=10.1017/S1551929514000029 |url=https://www.cambridge.org/core/services/aop-cambridge-core/content/view/E8B7456A024C6ED07D4E891F540C8EE2/S1551929514000029a.pdf/pioneers-in-optics-johann-wilhelm-ritter-and-ernest-rutherford.pdf |access-date=27 June 2023 |publisher=Cambridge University Press |s2cid=135584871 |archive-date=3 January 2023 |archive-url=https://web.archive.org/web/20230103220843/https://www.cambridge.org/core/services/aop-cambridge-core/content/view/E8B7456A024C6ED07D4E891F540C8EE2/S1551929514000029a.pdf/pioneers-in-optics-johann-wilhelm-ritter-and-ernest-rutherford.pdf |url-status=live }}</ref> Such deflection angles, although rare, were found. Reflecting on these results in one of his last lectures, Rutherford was quoted as saying: "It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."<ref>''The Development of the Theory of Atomic Structure'' (Rutherford 1936). Reprinted in [https://archive.org/details/backgroundtomode032734mbp/page/n85/mode/2up ''Background to Modern Science: Ten Lectures at Cambridge arranged by the History of Science Committee 1936'']</ref> It was Rutherford's interpretation of this data that led him to propose the [[Atomic nucleus|nucleus]], a very small, [[charge (physics)|charged]] region containing much of the atom's mass.<ref name=charge>{{Cite journal |last1=Rutherford |first1=E. |year=1911 |title=The scattering of α and β particles by matter and the structure of the atom |url=http://www.math.ubc.ca/~cass/rutherford/rutherford688.html |journal=The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science |series=Series 6 |volume=21 |issue=125 |pages=669–688 |doi=10.1080/14786440508637080 |access-date=6 October 2012 |archive-date=7 June 2012 |archive-url=https://web.archive.org/web/20120607013629/http://www.math.ubc.ca/~cass/rutherford/rutherford688.html |url-status=live }}</ref>

In 1912, Rutherford was joined by [[Niels Bohr]] (who postulated that electrons moved in specific orbits about the compact nucleus). Bohr adapted Rutherford's nuclear structure to be consistent with [[Max Planck]]'s quantum hypothesis. The resulting [[Rutherford–Bohr model]] was the basis for [[quantum mechanics|quantum mechanical]] atomic physics of Heisenberg which remains valid today.<ref name="Nobel Rutherford Biography"/>