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J. J. Thomson


Joseph John Thomson (J.J. Thomson) published his discovery of the first subatomic particle, called the electron in 1897. <ref>http://dbhs.wvusd.k12.ca.us/webdocs/AtomicStructure/Thomson-model-Intro.html</ref> The discovery was an outcome from a series of experiments in which he studied the nature of electric discharge in a high-vacuum cathode-ray tube (CRT).

Early Life

J.J. Thomson was born near Manchester, England (Cheetham Hill) on December 18th, 1856. He wanted from Scottish Parentage.<ref>http://www.web.visionlearning.com/events/JJThomson_Dec18_2004.htm)</ref> His father was Joseph James Thomson, a publisher and an antique bookseller and his mother was Emma Thomson who came from a family who owned a cotton spinning company. <ref> National Science Digital Library (1998-2008) Sir J.J. Thomson (1856 - 1940) Febuary 6, 2009 http://www.atomicarchive.com/Bios/Thomson.shtml</ref> Thomson's father wanted J.J. to be an engineer but he did not have the fee for his son's apprenticeship, there in 1870. Thomson enrolled to Owens College in Manchester at only the age of 14. At the college, J.J. studied engineering, mathematics, physics, and chemistry. On his second year of college, at the age of 16, his father died. Seeing his potential, his professor of mathematics encouraged Thomson to apply for a scholarship at Trinity College in 1880. During that year, he focused and stuided physics and experimented at the Cavendish Laboratory under Lord Rayleigh. He came second highest in his class, becoming a *Second Wrangler behind his fellow classmate Joseph Larmor (who was Senior Wrangler).<ref>http://www.aip.org/history/electron/jjthomston.htm</ref>, <ref> The Nobel Foundation (1906) Febuary 6, 2009 http://nobelprize.org/nobel_prizes/physics/laureates/1906/thomson-bio.html</ref>

Master of Trinity

Thomson retired as Cavendish Professor in 1919, having been appointed as Master of Trinity College a year earlier. Rutherford took over as Cavendish Professor, but Thomson became a special Professor of Physics who continued to work alongside Rutherford until the new Professor's premature death.Thomson himself died on 30th August, 1940. His ashes were buried in Westminster Abbey near the tombs of Isaac Newton, Charles Darwin, and his friend Rutherford.

Thomson received the Nobel physics prize in 1906 for his 'investigations of the passage of electricity through gases', and was knighted in 1908. He was President of the Royal Society from 1914-1916, President of the Institute of Physics from 1921-1923, and Master of Trinity College from 1918 until his death.

In 1890 he married Rose Paget, a former student. They had two children, George and Joan. Thomson was an unassuming and unpretentious man, despite his achievements and awards. His main hobby outside of his research was gardening. <ref> http://www-outreach.phy.cam.ac.uk/camphy/physicists/physicists_thomson.htm</ref>


The Cavendish Laboratory

This particular laboratory (where Thomson would soon experiment) was founded in 1871 by James Clerk Maxwell, the first Cavendish Professor. Maxwell was a man who developed thebasic equations of electromagnetism. Thomson was to be chosen as the Third Cavendish professor under Maxwell and Lord Rayleigh (who was the Second Cavendish Professor). Although Thomson wasn't very good in doing experiments, as time progressed, he learned quickly and conducted over many experimental physics at the Cavendish. Many important experiments on electromagnetism and atomic particles were performed in the laboratory and many physicists received their early training. Some of these physicists would later on happen to be seven Nobel Prize winners and 27 Fellows of the Royal Society. Thomson was very interested in the work of other researchers and would check daily on their progress and would often make suggestions for improvement. One of his students was Ernest Rutherford.

Marriage and Family

Being the chair of physics and professor at the Cavendish Laboratory, he met a lot of interesting and aspiring researchers. Among those researchers was a woman by the name of Rose Elisabeth Paget. Ms. Paget was one of the first generation of women permitted into advanced university stdies. After attending some of Thomson's lectures, she performed some experiments on soap films in 1889. Later on, J.J. Thomson and Rose Paget married on January 22, 1980. They had two children, George Paget Thomson and a daughter Joan Paget Thomson. George studied and worked under his father and won a Nobel prize meanwhile Joan just often traveled with her father.


Plum pudding model

J.J. Thomson abandoned his earlier vortex model and developed an atomic model in which he described negatively charge electrons scattered in a sphere shaped atom. Because the atom is not charged, he suggested a positively charges sphere around the atom. The positive charges were not scattered throughout and the protons were not discovered yet.

The 1904 model is named the plum pudding model. This model is in stark contrast to the Greeks' and John Dalton's model, suggesting the atom was a solid sphere. As was said before, this knowledge was gained by his many attempts with experimenting using the cathode-ray tube. Thomson said that the cathode ray tube produces a ray with constant charge to mass ratio and that all cathode ray tubes are composed of identically negatively charge particles which are now called electrons. He knew that they had a negative charge because he could show that they were repelled by the negative part of an electric field.<ref>http://thechembook.com/index.php/Lecture_Notes)</ref>

Accomplishments and Death

Later on as the time progessed, he was awareded the Nobel Prize in 1906 in the category of physics and was also knighted in 1908 as one of the fellows of the royal Society. His research and investigations resulted with the invention of the mass spectrometer by a man named Francis Aston. It's a device that allows the determination of the mass-to-charge ratio of ions. His teachings led to many of his students in becoming physicists, like Ernest Rutherford and Nobel Prize winners, such example would be his son. Inthe year 1918, Thomson became a Master of Trinity College in Cambridge where he stayed until his death on August 30, 1940. He is buried in Westminister Abbey, near Isaac Newton.<ref>http://www.experiment-resources.com/cathode-ray.html</ref>

Further Reading

ChemTeam

References

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See also

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