Strange Cloud: The Discovery of the Electron, Essay Example

When talking about anything relating to the atom, that invisible item composing every strand of matter in everything ever known, it is unreasonable – and a little foolish – to claim that one subatomic particle has more value than another. The atom is, all other points aside, too minute to carry within it anything not absolutely essential to making it an atom, and the list of all that goes into making it is a short one, anyway.

As the world knows, the atom is a core, or nucleus, of neutron and proton particles surrounded by an electron. There are unusual variations to the standard set-up: a hydrogen-1 atom, for instance, has no neutrons. Ultimately, however, the named trio is the foundation within all matter, and it only stands to reason that neutron, proton, and electron should be equally vital components.

They are. However, matter is never just any one thing, and the ways in which matter can be manifested, studied, and employed set the electron apart. In a sense, it is the “living” element within the inanimate atom, the particle of motion and ceaseless activity. “As a consequence of its lightness, charge, and stability, the electron has a unique importance to physics, chemistry, and biology” (Weinberg, 9).

Moreover, while the electron was the first subatomic particle to be scientifically identified, it has been the source of the greatest atomic mysteries. The electron behaves, as will be seen later, in ways that defy all principles of physics. It is in fact largely responsible for the scientific community’s need to face that, on the subatomic level, matter obeys rules completely of its own making. The accepted laws governing the conduct of matter do not apply, and the electron, even more than the other particles, operates in a realm of physics still largely not full understood. As will be seen, even its trajectories remain something of a mystery.

The ancient Greeks were, not surprisingly, the first to generalize a concept of atomic theory, and references to a single unit somehow at the heart of everything are common in Greek texts. Many centuries later, Western thinking would give increasing attention to the properties of electricity and magnetism, long having noted how certain substances in contact produce a charge of some kind. By the 19^th century, naturalist Richard Laming was closing in on the reality of the situation, and he speculated that atoms are composed of solid cores surrounded by units of electrical charges.

Various other scientific theories then arose, all interpreting Laming’s conclusion individually, while holding to its essence. It was in 1896, however, that scientist J. J. Thomson, in collaboration with John Townsend and H. A. Wilson, employed the study of cathode rays to prove a suspicion. The connection was relatively apparent; cathode rays, basically streams of energy evident when all gas is vacuumed out of a tube, were as problematic and inexplicable as atoms had been. The cathode ray did not fit into known science, which held that the atom was a purely indivisible particle unto itself. There could be nothing producing the cathode “beam” if all the matter within the tube was evacuated, yet the cathode ray was clearly there.

In order to formulate an effective series of experiments, Thomson leaned on the work of Philipp Lenard. Lenard had devised a means to make the study of cathode rays accessible. The tubes previously employed allowed air in, yet were too sealed to permit proper inspection. Creating a tube with small windows in the tube glass, thin enough to allow the rays to pass through, was Lenard’s solution. This allowed for the freedom to pass the rays into completely vacuumed environments, and then be monitored for intensity.

What captured Thomson’s attention was that Lenard’s rays traveled much farther than any atomic-sized particle should be able to. It was evident that something smaller, something not in keeping with the concept of the indivisible atom, was at play, and Thomson was the first to conceptualize the subatomic particle. It then became merely a matter of proving that such matter could exist.

What his experiment required, then, was a determination of the actual mass of the cathode energy, and he estimated this by measuring the heat produced when the cathode rays hit a thermal junction, and  then by comparing the heat level with the magnetic deflection of the rays themselves. In this way, he could arrive at an electron “weight”, and in the doing confirm the existence of the particle itself. It was a marriage of physics and mathematics on both a high order and an elementary plane.

Thomson’s work revolutionized scientific thinking in regard to the atom, and in a number of ways. For one thing, it established the first evidence that the atom was a composition, and not a single unit. Not unexpectedly, the discovery of this first subatomic particle, the electron, generated massive efforts to isolate the others. The Thomson revelation sparked a global focus on atomic study within the scientific community, and one which would require only a few decades to complete the work.

The further discoveries of the proton and the neutron, and how they serve in the atom’s composition, helped to better define the electron itself. Essentially, a final view of the whole, if infinitesimal, picture placed the electron firmly in place, or as much as so ephemeral a particle could be placed: “In 1932, the discovery of the neutron put paid to the idea that electrons exist within the nucleus at the heart of the atom” (Sutton, 49). Further science led to more distinct knowledge, and more defined subatomic interplay, or lack thereof: “Nearly four decades elapsed between the discovery of the electron and the recognition that the electron is only a minor participant in nuclear interactions…and plays no role in nuclear structure” (Warwick, 307).

Each revelation, however, only gave rise to new mysteries. Certain properties made sense, as in the relationships between the atomic charges: “The light mobile electrons contained in all matter are always negatively charged, while the positive charge is attached to the heavy part of the matter, to the atomic nuclei…” (Frisch, 139). Here, at least, was evidence the there was universality in the basic precepts of physics.

However, in determining that the electron was so light, a different perspective was needed to consider the essence of matter itself. “ The mass (weight) of an electron is approximately equal to 1/1836 that of a hydrogen atom, which has one electron and one proton, so an electron is 1/1836th the size of a proton” (Northwestern). This is minute on a scale that is incomprehensible to the human mind, even more so than the atom. Moreover, the nature of the particle, again, called for a new definition of matter, as it seems to incorporate within itself aspects of both energy and matter.

It would require a great deal of work, and from the greatest minds in physics, to begin to understand the implications of this new anomaly. “Thomson’s careful experiments and adventurous hypotheses were followed by crucial experimental and theoretical work by many others in the United Kingdom, Germany, France and elsewhere” (AIP ). The electron, as the first discovered subatomic particle, also won the distinction of being the first atomic discovery to make clear that existing theories were inadequate to explain it.

The most evident and troubling dilemma, once it was understood that the electron orbits the nucleus of the atom, was in how, essentially, it could keep doing so. Electrodynamic theory demanded that it quickly run out of energy and then collide into the nucleus. By all known science, no electron should be able to sustain an orbit beyond the most fractional instant.

In 1913, physicist Niels Bohr proposed a solution which would, in addressing this problem with the workings of the electron, open the door to what would become all quantum theory. Having studied the spectrum readings of hydrogen particles fired at foil, Bohr was intrigued to note that the wavelengths of recorded energy were strangely inconsistent. More exactly, at some wavelengths, it appeared that no energy was being emitted by the particles. Put unscientifically, it was like a magic act on an atomic scale; there were sudden and completely inexplicable appearances and disappearances.

A new way of thinking, essentially, had to be devised to account for this. In his paper, “On the Constitutions of Atoms and Molecules”, Bohr suggested the then-radical concept that electrons could orbit in a non-linear fashion; they could be in one place and then another, but never actually exist in the intervening spaces. This was, as stated, the birth of the “quantum leap”, and the theory won Bohr the 1922 Nobel Prize in physics. As bizarre in scientific terms as the theory was, it made sense, because it was the only logical means of explaining why electrons do not spiral into the nucleus. By orbiting in this quantum way, they never precisely orbit, and are therefore not liable to the electrodynamic expectations of an ordinary orbit.

From this theory, the prevailing notion of the electron as a single particle spinning around an atom’s nucleus, much as a moon circles a planet, was abandoned. What is now believed is that, were a person able to see an atom in its actual dimensions, the aspect would be that of a cloud. The movement of the electron is extraordinarily rapid; most models, including Bohr’s, have electrons going at very nearly the speed of light. When the size of the activity is considered, this is velocity at an unimaginable level. Consequently, a cloud would be evident because, in a sense, the electron circling the nucleus is everywhere and nowhere at once.

The discovery of the electron, while immeasurably influential in moving science forward, has just as effectively frustrated it. The properties of this single, negatively-charged, virtually weightless particle have stymied the greatest minds in physics, and to this day. Even Quantum Theory, created out of the necessity to account for the electron, remains a disputed realm within physics, and one never accepted by Albert Einstein. With the electron came a new world within science, and one which had to confront the distinct possibility that science is vastly impacted by that which is not science. Physics has had, in some measure, share space with metaphysics, for the uncanny properties of the electron cloud defy logical, rational explanation.

This, however, may be the greatest legacy of the electron’s discovery. Given the stretching of thinking and the openness to the unusual the study of this particle has demanded, no physicist can ever again safely assert universal laws of physics applicable to all matter. Because of the electron, man has learned that the elements can confound him on levels previously thought of as immutable. With doubt, then, comes further research, and a necessary understanding of the limits of what we can think we truly know.

Works Cited

American Institute of Physics. “A Look Inside the Atom”. http://www.aip.org/history/electron/jjhome.htm  Retrieved January 27, 2011.

Qualitative Reasoning Group, Northwestern University.  Retrieved January 27, 2011. http://www.qrg.northwestern.edu/projects/vss/docs/power/2-whats-an-electron.html

Frisch, O. R. “Parity Is Not Conserved: A New Twist to Physics.” Bulletin of the Atomic  Scientists,  March, 1959: 139-144. Print.

Sutton, C. “Ninety Years Around the Atom.” New Scientist Magazine, Jan. 8, 1987: 49-53. Print.

Warwick, A. Histories of the Electron: The Birth of Microphysics. Cambridge, MA: MIT Press, 2004. Print.

Weinberg, S. The Discovery of Subatomic Particles. New York, NY: Cambridge University Press, 2006. Print.