Joseph John Thomson

December 18, 1856 in Manchester (England) – August 30, 1940 in Cambridge (England)

Thomson studied engineering in 1870 at Owens College and transferred to Trinity College, Cambridge to obtain his BA in 1880 in Mathematics (Second Wrangler and second Smith Prize) and his Master of Arts (earning the Adams Prize) in 1883.

In 1884 he became Professor of Physics at Cavendish. One of his students was Ernest Rutherford, who would later succeed him in the post. Thomson was elected a Fellow of the Royal Society that same year and subsequently served as its President from 1915 to 1920.

In 1890 he married Rose Elizabeth Paget, daughter of Sir Edward George Paget, and had two children, George and Joan Paget Thomson. His son became a noted physicist, who in turn was awarded the Nobel Prize in Physics in 1937 for demonstrating the wave-like properties of electrons.

Thomson carried out a series of experiments with cathode ray tubes that led him to discover the electron in 1897 and to propose a second model (the first was proposed by Dalton in 1794) in which the electrons had negative charges and were inside the atom, which had a positive charge.

Tubo catódico_Thomson

For this, there were three experiments in which he used cathode ray tubes, in the first instance, he demonstrated that electric fields were capable of generating their deviation and then he experimented with the deviation from the combined effect of electric and magnetic fields. , what was sought was to show the relationship between the charge and the mass of the particles, which remained constant despite the alteration of the cathode material.

Following the same studies and experiments, in 1897, Thomson would discover a new particle, which was a thousand times lighter than hydrogen, the aforementioned particle was called an electron. His discovery led him to be the first scientist to discover subatomic particles.

Modelo Pudin de Pasas de Thomson

Thomson's conclusions were bold: cathode rays were made of particles he called "corpuscles," and these corpuscles came from within the atoms of the electrodes, meaning that the atoms are, in fact, divisible. Thomson imagined that the atom is made up of these corpuscles in a sea full of positive charge; This model of the atom, attributed to Thomson, was called the "Raisin Pudding" model.

The impossibility of explaining that the atom is made up of a compact nucleus and an outer part called the shell implies that other scientists such as Ernest Rutherford or Niels Bohr continued their research and established other theories in which atoms had differentiated parts.

In 1906 he was awarded the Nobel Prize in Physics in 1906 for his theoretical and experimental investigations in the conduction of electricity generated by gases. Additionally, he was knighted in 1908 and of the Order of Merit in 1912.

In the same year, he showed that hydrogen has a single electron, confirming or rejecting various previous theories about the number of electrons.

Inventor of positive rays, in 1911, he discovered how to use them to separate atoms of different mass. He did this by deflecting the positive rays using electric and magnetic fields (mass spectrometry). Thus he discovered that neon has two isotopes (neon-20 and neon-22).

In 1918 he was appointed rector of Trinity College, Cambridge, where he met Niels Bohr, and remained until his death. He died on August 30, 1940 and was buried in Westminster Abbey near Sir Isaac Newton.

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