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JJ Thompson was born in 1856

Cheetham Hill, near Manchester, England—died August 30, 1940, Cambridge, Cambridgeshire) was an English physicist who helped revolutionize the knowledge of atomic structure by his discovery of the electron(1897). He received the Nobel Prize for Physics in 1906 and was knighted in 1908. Thomson determined that all matter is made up of tiny particles that are much smaller than atoms. He originally called these particles 'corpuscles,' although they are now called electrons. This discovery upended the prevailing theory that the atom was the smallest fundamental unit.

In 1906, Thomson began studying positively charged ions, or positive rays. This led to one of his other famous discoveries in 1912 when he channeled a stream of ionized neon through a magnetic and an electric field and used deflection techniques to measure the charge to mass ratio. In doing so, he discovered that neon was composed of two different kinds of atoms, and proved the existence of isotopes in a stable element. This was the first use of mass spectrometry.

Best Known For: J.J. Thomson was a Nobel Prize-winning physicist whose research led to the discovery of electrons.

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Thomson atomic model, earliest theoretical description of the inner structure of atoms, proposed about 1900 by William Thomson (Lord Kelvin),and strongly supported by Sir Joseph John Thomson

Thomson held that atoms are uniform spheres of positively charged matter in which electrons are embedded. Popularly known as the plum pudding model, it had to be abandoned (1911) on both theoretical and experimental grounds in favour of the Rutherford atomic model, in which the electrons describe orbits about a tiny positive nucleus.

A plum pudding model is a historical scientific model of the atom that was proposed by J.J. Thomson in 1904, shortly after he discovered the electron. The model tried to explain two properties of atoms that were known at that time: electrons are negatively charged particles, and atoms have no net electric charge.

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Major contribution of Plum pudding theory

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Major contribution of Plum pudding theory

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Major contribution of Milikan's Experiment

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Major contribution of Milikan's Experiment

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the accurate determination of the elementary electric charge—the charge of a single electron. Before Millikan's experiment in 1909, the exact value of the electron's charge was not well established. His work demonstrated that electric charge is quantized, meaning it exists in discrete units. Through the experiment, Millikan measured the charge of individual oil droplets suspended between two electrically charged plates and found that the charge on each droplet was always a multiple of a fundamental value, which he concluded to be the charge of a single electron (approximately 1.602×10−191.602×10−19 coulombs).

This discovery was pivotal in advancing atomic theory, as it provided crucial evidence that electrons are fundamental particles of nature with a consistent, unchangeable charge. Millikan’s experiment also helped refine the understanding of atomic structure and contributed to the development of quantum mechanics.

Additionally, his findings helped confirm Robert A. Millikan's earlier work on Planck's constant and energy quantization in photoelectric effect studies, further supporting emerging quantum theories. For this work, Millikan was awarded the Nobel Prize in Physics in 1923.

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oil experiment