EUGEN GOLDSTEIN: DISCOVERIES AND CONTRIBUTIONS - PHYSICAL - 2025

Eugen Goldstein was a prominent German physicist, born in present-day Poland in 1850. His scientific work includes experiments with electrical phenomena in gases and cathode rays.

Goldstein identified the existence of protons as equal and opposite charges to electrons. This discovery was made through experimentation with cathode ray tubes, in 1886.

Beam of electrons are directed from the cathode to the anode.

One of his most outstanding legacies consisted in the discovery of what today are known as protons, together with channel rays, also known as anodic or positive rays.

Was there a Goldstein atomic model?

Godlstein did not propose an atomic model, although his discoveries allowed the development of Thomson's atomic model.

On the other hand, he is sometimes credited as the discoverer of the proton, which he observed in the vacuum tubes where he observed cathode rays. However, Ernest Rutherford is considered the discoverer in the scientific community.

Cathode ray experiments

Crookes tubes

Goldstein began his experiments with Crookes tubes in the 1970s. Then, he made modifications to the structure developed by William Crookes in the 19th century.

The basic structure of the Crookes tube consists of an empty tube made of glass, inside which gases circulate. The pressure of the gases inside the tube is regulated by moderating the evacuation of the air inside it.

The apparatus has two metal parts, one at each end, which act as electrodes, and both ends are connected to external voltage sources.

By electrifying the tube, the air ionizes and becomes a conductor of electricity. Consequently, the gases become fluorescent when the circuit between the two ends of the tube is closed.

Crookes concluded that this phenomenon was due to the existence of cathode rays, that is to say, flow of electrons. With this experiment the existence of elementary particles with negative charge in the atoms was demonstrated.

Modification of Crookes tubes

Goldstein modified the structure of the Crookes tube, adding several perforations to one of the metal cathodes in the tube.

In addition, he repeated the experiment with the modification of the Crookes tube, increasing the voltage between the ends of the tube to several thousand volts.

Under this new configuration, Goldstein discovered that the tube emitted a new glow from the end of the tube that had been pierced.

However, the highlight is that these rays were moving in the opposite direction to the cathode rays and were called channel rays.

Goldstein concluded that, in addition to the cathode rays, which traveled from the cathode (negative charge) towards the anode (positive charge), there was another ray that traveled in the opposite direction, that is, from the anode towards the cathode of the modified tube.

In addition, the behavior of the particles in regard to their electric field and magnetic field, was totally opposite to that of cathode rays.

This new flow was baptized by Goldstein as channel rays. Because the channel rays traveled in the opposite direction to the cathode rays, Goldstein inferred that the nature of their electrical charge must also be the opposite. That is, the channel rays were positively charged.

Channel rays

Channel rays arise when cathode rays collide with atoms in the gas that is confined within the test tube.

Equally charged particles repel each other. Starting from this base, the electrons of the cathode ray repel the electrons of the gas atoms, and the latter are released from their original formation.

The gas atoms lose their negative charge, and become positively charged. These cations are attracted to the negative electrode of the tube, given the natural attraction between opposite electrical charges.

Goldstein named these rays "Kanalstrahlen" to refer to the counterpart of cathode rays. The positively charged ions that make up the channel rays move towards the perforated cathode until they pass through it, given the nature of the experiment.

Hence, this type of phenomenon is known in the scientific world as channel rays, since they pass through the existing perforation in the cathode of the study tube.

Modification of cathode tubes

Likewise, Eugen Godlstein's essays also contributed significantly to deepening technical notions about cathode rays.

Through experiments in evacuated tubes, Goldstein found that cathode rays could cast sharp shadows of emission perpendicular to the area covered by the cathode.

This discovery was very useful to modify the design of the cathode tubes used to date, and to place concave cathodes in their corners, to produce focused rays that would be used in a variety of applications in the future.

Channel rays, also known as anodic rays or positive rays, depend directly on the physical-chemical characteristics of the gas that is contained within the tube.

Consequently, the relationship between the electric charge and the mass of the particles will be different depending on the nature of the gas that is being used during the experiment.

With this conclusion, the fact that the particles came out of the interior of the gas, and not of the anode of the electrified tube, was clarified.

Goldstein contributions

First steps in the discovery of the proton

Based on the certainty that the electric charge of atoms is neutral, Goldstein took the first steps to verify the existence of positively charged fundamental particles.

Foundations of modern physics

Goldstein's research work brought the foundations of modern physics with them, since the demonstration of the existence of channel rays allowed to formalize the idea that atoms moved quickly and with a specific pattern of movement.

This type of notion was key in what is now known as atomic physics, that is, the field of physics that studies the behavior and properties of atoms in their entirety.

Isotope study

Thus, Goldstein's analyzes gave rise to the study of isotopes, for example, among many other scientific applications that are in full force today.

However, the scientific community attributes the discovery of the proton to the New Zealand chemist and physicist Ernest Rutherford in mid-1918.

The discovery of the proton, as the counterpart of the electron, laid the foundations for the construction of the atomic model that we know today.

References

1. Canal Ray Experiment (2016). Recovered from: byjus.com
2. The atom and atomic models (nd). Recovered from: recursostic.educacion.es
3. Eugen Goldstein (1998). Encyclopædia Britannica, Inc. Recovered from: britannica.com
4. Eugen Goldstein (nd). Recovered from: chemed.chem.purdue.edu
5. Proton (sf). Havana Cuba. Recovered from: ecured.cu
6. Wikipedia, The Free Encyclopedia (2018). Eugen Goldstein. Recovered from: es.wikipedia.org
7. Wikipedia, The Free Encyclopedia (2018). Crookes tube. Recovered from: es.wikipedia.org