The debate about who opened the electron has not subsided so far. In the role of the discoverer of an elementary particle, in addition to Joseph Thomson, some science historians see Hendrick Lorentz and Peter Zeeman, others Emil Wiechert, and others Philip Lenard. So who is he, the scientist who discovered the electron?
Atom means indivisible
The concept of "atom" was introduced by philosophers. The ancient Greek thinker Leucippus back in the 5th century BC. e. suggested that everything in the world is made up of the smallest particles. His student, Democritus, called them atoms. According to the philosopher, atoms are the "bricks" of the universe, indivisible and eternal. The properties of substances depend on their shape and external structure: atoms of flowing water - smooth, metal - with profile teeth, which give hardness to the body.
The outstanding Russian scientist M.V. Lomonosov, the founder of the atomic-molecular theory, believed that in the composition of simple substances the corpuscles (molecules) are formed by one kind of atom, complex - different.
Chemist taught John Dalton (Man) in 1803, at based on experimental data and taking the standard unit weight of the hydrogen atoms found relative atomic masses of some elements. The atomic theory of the Englishman was of great importance for the further development of chemistry and physics.
Who is the electron open to?
By the beginning of the 20th century, a whole series of experimental data had been accumulated, proving the complexity of the structure of the atom. This may include the phenomenon of the photoelectric effect (G. Herz, A. Stoletov 1887), the discovery of the cathode (J. Plücker, V. Crookes, 1870) and x-ray (V. Roentgen, 1895) rays, radioactivity (A. Becquerel, 1896).
Scientists working with cathode rays were divided into two camps: some suggested the wave nature of the phenomenon, the other corpuscular. The tangible results were achieved by the professor of the Higher Normal School (Lille, France) Jean Baptiste Peren. In 1895, he showed during experiments that cathode rays are a stream of negatively charged particles. Is Peren the physicist who discovered the electron?
On the threshold of great achievements
Physicist and mathematician George Stoney (Royal University of Ireland, Dublin) in 1874 voiced the assumption of discreteness of electricity. In what year and by whom was the electron discovered? During the experimental work on electrolysis, it was D. Stoney who determined the value of the minimum electric charge (although the result obtained (10 -20 C) was 16 times less than the real one). The unit of elementary electric charge in 1891, the Irish scientist called the "electron" (from the ancient Greek "amber").
A year later, Gendrick Lawrence (Leiden University, the Netherlands) formulated the main provisions of his electronic theory, according to which the structure of any substance is based on discrete electric charges. These scientists are not considered the discoverer of the particle, but their theoretical and practical research has become a reliable foundation for the future discovery of Thomson.
Unwavering enthusiast
When asked who and when discovered the electron, encyclopedias give a clear and unambiguous answer - Joseph John Thomson in 1897. So what is the merit of the English physicist?
The father of the future president of the Royal Society of London was a seller of books and from childhood he instilled in his son a love of the printed word and a craving for new knowledge. After graduating from Owens College (from 1903 - University of Manchester) and Cambridge University in 1880, the young mathematician Joseph Thomson joined the Cavendish Laboratory. Experimental studies completely captivated the young scientist. Colleagues noted his tirelessness, determination and extraordinary dedication to practical work.
In 1884, at the age of 28, Thomson was appointed director of the laboratory, replacing Lord C. Rayleigh. Under the direction of Thomson, the laboratory over the next 35 years turned into one of the largest centers of world physics. From here E. Rutherford, N. Bohr, P. Langevin began their journey.
Attention to detail
Thomson began his work on the study of cathode rays by testing the experiments of his predecessors. For many experiments, special equipment was made according to the personal drawings of the laboratory director. Having received high-quality confirmation of the experiments, Thomson did not think to stop there. He saw his main task in accurately quantifying the nature of the rays and their constituent particles.
The new tube, designed for the following experiments, included not only the usual cathode and accelerating electrodes (in the form of plates and rings) with a deflecting voltage. The flow of particles was directed to the screen, covered with a thin layer of a substance that glows upon impact of particles. The flow was supposed to control the combined effects of electric and magnetic fields.
Atom constituents
It’s hard to be a discoverer. It is even more difficult to defend one’s beliefs that run counter to millennia-old concepts. Belief in yourself, in your team, made Thomson the person with whom the electron is open.
The experience yielded stunning results. The mass of particles turned out to be 2 thousand times less than that of hydrogen ions. The ratio of the charge of the corpuscle to its mass does not depend on the flow rate, the properties of the cathode material, the nature of the gas medium in which the discharge occurs. A conclusion was drawn that contradicts all the foundations: corpuscles are universal particles of matter in an atom. Time after time, Thomson diligently and carefully checked the results of experiments and calculations. When there was no doubt, a report was made on the nature of the cathode rays of the Royal Society of London. In the spring of 1897, the atom ceased to be indivisible. In 1906, Joseph Thomson was awarded the Nobel Prize in Physics.
Unknown Johann Wiechert
The name of the teacher of geophysics at Köningsbörsky, and then the University of Göttingen, Johann Emil Wiechert, researcher of the seismography of our planet, is better known in professional circles of geologists and geographers. But he is also familiar to physicists. This is the only person whom official science, along with Thomson, recognizes as the discoverer of the electron. And to be absolutely precise, the work with the description of Wyhert’s experiments and calculations was published in January 1897 - four months before the Englishman’s report. Who discovered the electron is already historically decided, but the fact remains.
For reference: Thomson did not use the term "electron" in any of his works. He used the name "corpuscles."
Who discovered the proton, neutron and electron?
After the discovery of the first elementary particle, assumptions about the possible structure of the atom began to be advanced. One of the first models was proposed by Thomson himself. The atom, he said, resembles a piece of pudding with raisins: negative particles are interspersed in a positively charged body.
In 1911, Ernest Rutherford (New Zealand, UK) suggested that the atom model has a planetary structure. Two years later, he put forward a hypothesis about the existence of a positively charged particle in the atomic nucleus and, having received it experimentally, called it a proton. He predicted the presence of a neutral particle with a proton mass in the nucleus (a neutron was discovered in 1932 by the English scientist J. Chadwick). In 1918, Joseph Thomson transferred the management of the laboratory to Ernest Rutherford.
Needless to say, the discovery of an electron made it possible to take a fresh look at the electrical, magnetic, and optical properties of matter. It is difficult to overestimate the role of Thomson and his followers in the development of atomic and nuclear physics.