{"id":4383,"date":"2024-09-22T17:07:33","date_gmt":"2024-09-22T17:07:33","guid":{"rendered":"https:\/\/workhouse.sweetdishy.com\/?p=4383"},"modified":"2024-09-22T17:07:34","modified_gmt":"2024-09-22T17:07:34","slug":"rutherfords-planetary-model-of-the-atom","status":"publish","type":"post","link":"https:\/\/workhouse.sweetdishy.com\/index.php\/2024\/09\/22\/rutherfords-planetary-model-of-the-atom\/","title":{"rendered":"RUTHERFORD\u2019S PLANETARY MODEL OF THE ATOM"},"content":{"rendered":"\n

Rutherford came up with a new model of the atom that accounted for his scattering results: he proposed that the positive charge and its associated mass is concentrated in the nucleus, and that the negatively charged electrons are orbiting around it, like planets. In his 1911 paper discussing the alpha-particle scattering results,20<\/sup> Rutherford mentioned the planetary atomic model that had been proposed back in 1904 by Japanese physicist Hantaro Nagaoka.<\/p>\n\n\n\n

Nagaoka was inspired by the structure of Saturn, and imagined the atom could have a very massive nucleus, analogous to the massive nature of Saturn (Figure 75). Electrons would revolve around the nucleus bound by electrostatic forces, just like Saturn\u2019s rings revolve around the planet bound by gravitational forces.<\/p>\n\n\n\n

Figure 75\u00a0The planetary model of the atom.\u00a0(a)<\/strong>\u00a0In 1904, Hantaro Nagaoka proposed a model of the atom based on an analogy with the rings of Saturn. He proposed the existence of a very massive nucleus (analogous to a very massive planet), and electrons revolving around the nucleus, bound by electrostatic forces (analogous to the rings revolving around Saturn, bound by gravitational forces). This model was mentioned by Rutherford in his 1911 paper, in which he announced the discovery of the nucleus.\u00a0(b)<\/strong>\u00a0Despite its inaccuracy, the Rutherford model caught the imagination of the public, and is still used as a symbol for atoms and atomic energy.\"\"<\/p>\n\n\n\n

Nagaoka believed that such a system would be stable, analogous to Saturn\u2019s rings, which remain steady because they orbit a very, very massive planet. However, the problem with this assumption is that electrons, unlike Saturn\u2019s rings, are electrically charged.<\/p>\n\n\n\n

The issue is that the electrons in the planetary model move in circles. You may remember from basic physics that if a body is moving around a circle, even if it is moving at a constant speed it is accelerating. This is because it is changing direction (it isn\u2019t moving in a straight line). Now, Maxwell\u2019s equations of electromagnetism predict that accelerating electric charges should emit electromagnetic waves. As such, the electrons in the planetary model should lose energy by radiating electromagnetic waves. Then, like a satellite losing energy because of friction with Earth\u2019s upper atmosphere, the electrons should quickly spiral to their death into the nucleus (Figure 76). All atoms in the universe would have disappeared just an instant after their creation!<\/p>\n\n\n\n

Figure 76\u00a0The planetary model of the atom is inherently unstable. This is because an orbiting electron is an electric charge under acceleration, and must therefore radiate electromagnetic energy at the cost of centrifugal force. The electron in this model would thus spiral to its death in a very small fraction of a second.\"\"<\/p>\n\n\n\n

In the next chapter, we will see how quantum physics comes to the rescue by explaining how electrons may nevertheless remain in stable orbits around the nucleus.<\/p>\n","protected":false},"excerpt":{"rendered":"

Rutherford came up with a new model of the atom that accounted for his scattering results: he proposed that the positive charge and its associated mass is concentrated in the nucleus, and that the negatively charged electrons are orbiting around it, like planets. In his 1911 paper discussing the alpha-particle scattering results,20 Rutherford mentioned the planetary […]<\/p>\n","protected":false},"author":1,"featured_media":4174,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[513],"tags":[],"class_list":["post-4383","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-atoms-and-radioactivity"],"jetpack_featured_media_url":"https:\/\/workhouse.sweetdishy.com\/wp-content\/uploads\/2024\/09\/atom-2.png","_links":{"self":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts\/4383","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/comments?post=4383"}],"version-history":[{"count":1,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts\/4383\/revisions"}],"predecessor-version":[{"id":4384,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts\/4383\/revisions\/4384"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/media\/4174"}],"wp:attachment":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/media?parent=4383"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/categories?post=4383"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/tags?post=4383"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}