The debate about who discovered the electron has not subsided so far. In the role of the discoverer of the elementary particle, besides Joseph Thomson, some historians of science see Hendrik Lorentz and Peter Zeeman, others - Emil Wiechert, still others - Philip Lenard. So who is the scientist who discovered the electron?
Atom means indivisible
The concept of "atom" was introduced into use by philosophers. The ancient Greek thinker Leucippus in the 5th century BC. e. suggested that everything in the world is made up of tiny 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: the atoms of flowing water are smooth, those of metal have profile teeth that 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, corpuscles (molecules) are formed by one type of atoms, while complex ones are different.
Self-taught chemist John D alton (Manchester) in 1803, relying onexperimental data and, taking the mass of hydrogen atoms as a conventional unit, established the relative atomic masses of some elements. The atomistic theory of the Englishman was of great importance for the further development of chemistry and physics.
Who discovered the electron?
By the beginning of the 20th century, a number of experimental data had been accumulated, proving the complexity of the structure of the atom. These include the phenomenon of the photoelectric effect (G. Hertz, A. Stoletov 1887), the discovery of cathode (Yu. Plyukker, V. Kruks, 1870) and X-ray (V. Roentgen, 1895) rays, radioactivity (A. Becquerel, 1896).
Scientists who worked with cathode rays divided into two camps: some assumed the wave nature of the phenomenon, others - corpuscular. Tangible results were achieved by the professor of the Higher Normal School (Lille, France) Jean Baptiste Peren. In 1895, he showed through experiments that cathode rays are a stream of negatively charged particles. Maybe Peren is the physicist who discovered the electron?
On the verge of great things
Physicist and mathematician George Stoney (Royal Irish University, Dublin) in 1874 voiced an assumption about the discreteness of electricity. In what year and by whom was the electron discovered? In the course of experimental work on electrolysis, it was D. Stoney who determined the value of the minimum electric charge (however, the result obtained (10-20 C) was 16 times less than the actual one). In 1891, an Irish scientist called the unit of elementary electric charge "electron" (from the ancient Greek"amber").
A year later, Hendrik 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 became a reliable foundation for Thomson's future discovery.
Relentless Enthusiast
On the question of 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 bookseller and from childhood instilled in his son a love for the printed word and a craving for new knowledge. After graduating from Owens College (since 1903 - the University of Manchester) and the University of Cambridge in 1880, the young mathematician Joseph Thomson joined the Cavendish Laboratory. Experimental studies completely captivated the young scientist. Colleagues noted his indefatigability, determination and extraordinary passion for practical work.
In 1884, at the age of 28, Thomson was appointed director of the laboratory, succeeding Lord C. Rayleigh. Under the leadership of Thomson, the laboratory in the next 35 years has become one of the largest centers of world physics. E. Rutherford, N. Bohr, P. Langevin started their journey from here.
Attention to detail
Thomson began his work on the study of cathode rays by checking experimentshis predecessors. For many experiments, special equipment was made according to the personal drawings of the director of the laboratory. Having received qualitative confirmation of the experiments, Thomson did not think to stop there. He saw his main task in the exact quantitative determination of 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 corpuscles was directed to a screen covered with a thin layer of matter that glowed when the particles hit. The flow was supposed to be controlled by the combined effect of electric and magnetic fields.
Parts of an atom
It's hard to be a pioneer. It is even more difficult to defend one's convictions, which run counter to the concepts that have been established for millennia. Faith in yourself, in your team, made Thomson the person who discovered the electron.
Experience gave 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 a corpuscle to its mass does not depend on the flow rate, the properties of the cathode material, or the nature of the gaseous medium in which the discharge occurs. A conclusion was suggested that contradicted all foundations: corpuscles are universal particles of matter in the composition of an atom. Time after time, Thomson diligently and carefully checked the results of experiments and calculations. When there was no doubt left, a report was made on the nature of cathode rays to the Royal Society of London. In the spring of 1897, the atomceased to be indivisible. In 1906, Joseph Thomson was awarded the Nobel Prize in Physics.
Unknown Johann Wiechert
The name of Johann Emil Wiechert, a professor of geophysics at Köningsbör and then Göttingen University, a researcher of our planet's seismography, 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 describing Wiechert's experiments and calculations was published in January 1897 - four months earlier than the Englishman's report. Who discovered the electron has already been 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 began to be made about the possible structure of the atom. One of the first models was proposed by Thomson himself. An atom, he says, is like a piece of raisin pudding: negative particles are embedded in a positively charged body.
In 1911, Ernest Rutherford (New Zealand, Great Britain) suggested that the model of the atom has a planetary structure. Two years later, he put forward a hypothesis about the existence of a positively charged particle in the nucleus of an atom and, having obtained it experimentally, called it a proton. He also predicted the presence in the nucleus of a neutral particle with the mass of a proton (the neutron was discovered in 1932 by the English scientist J. Chadwick). In 1918, Joseph Thomson handed over the management of the laboratory to Ernest Rutherford.
Is it necessary to say that the discovery of the electron allowed us 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.
