Atomic Theory

Unimaginably small units of matter. The building blocks of the universe. One of the most basic units of existence. Unimaginably small units of matter. The knowledge of atoms is some of the most pertinent information for the existence and development of human life, and science as a whole. Simply knowing and understanding these minuscule pieces of the universe that make up humans, the earth, and nearly everything known to man is of massive importance. If humans purely focused on what exists on a macroscopic scale, incredibly vast amounts of knowledge would be left untouched and unknown. The absolute significance of this knowledge in particular is the role of atoms in every aspect of existence, human and otherwise. Presently, it is nearly inconceivable to imagine a time when the existence of what made up of human life was not known. Not only does atomic knowledge assist in explaining the origin behind nearly everything, but also creates limitless possibilities for further research and development into discovering, harnessing, and utilizing atoms to advance human existence. The accumulation of the present knowledge of the atom is one of the greatest human feats, but it did not happen instantly. Over many hundreds of years, Notables and other scientists alike have invented and improved models of the atom, all to get it to where it is today. This story begins more than two thousand years ago in ancient Greece.

Democritus, an extremely knowledgeable man for his era, was Greek philosopher who made some of the first strides in the development of the atomic theory. At this time, the only way to discover more about the nature of matter was to theorize, and conduct extremely primitive empirical experiments. It was through his unquenchable curiosity and desire to learn that Democritus derived his simple sea shell experiment. He conducted this experiment by simply breaking a seashell in half repeatedly until he was finally left with a fine white powder, which he was unable to break apart any further. Discovering what he thought were bits of indivisible matter, Democritus dubbed these extremely small pieces “atoms”, which simply means “indivisible” in Greek. With assistance from his mentor Leucippus, he compiled a primitive atomic theory, consisting of several rules:

1. All matter consists of invisible particles called atoms.

2. Atoms are indestructible.

3. Atoms are solid but invisible.

4. Atoms are homogeneous.

5. Atoms differ in size, shape, mass, position, and arrangement.

Based on his observations of different substances in the world around him, he also theorized that solids were made of small, pointy atoms, that liquids were made of large, round atoms, and that oils were made of small, fine atoms that could easily slip past each other. Thousands of years later it is known that many of Democritus’ hypotheses have been proven untrue, but his accomplishments still stand as a reminder of the beginnings of the atomic theory. It is for providing the initial leap into the atomic realm that Democritus is recognized as a Cromulist Notable.

It is clear that the development of the atomic theory has not remained in 370 B.C with Democritus, but the next major development came approximately two millennia later, with John Dalton. A professor and public lecturer, Dalton was a successful scientist, discovering colour blindness in his early scientific years, and developing his theory regarding the nature of atoms later. Unlike Democritus, Dalton has significantly more advanced technology at his disposal for experimentation. In order to investigate his ideas regarding matter, he conducted multiple experiments in which he combined different types of gases. In these experiments, he discovered that gases could be mixed with each other, but only with set proportions. This meant that not only were there particles with spaces between them, allowing for mixture, but different particles had different properties, like mass. From these observations, among others, Dalton theorized multiple atomic rules:

1. All matter consists of tiny particles called atoms.

2. Atoms are indestructible and unchangeable.

3. Elements are characterized by the weight of their atoms.

4. In chemical reactions, atoms combine in small, whole-number ratios.

5. When elements react, their atoms may combine in more than one whole-number ratio.

Similar to Democritus, not all of Dalton’s theories have proven to be entirely correct, but his advancements in discovering the nature and behaviour of atoms is quite revolutionary. Beyond Democritus, Dalton created the more complex laws he believed that atoms abided by, and introduced his model of the atom, dubbed the “billiard ball model” due to its spherical shape. Because of his dedication, wit, and academic breakthroughs, Dalton embodies many Cromulist values, allowing him to become a Notable.

From Dalton’s model, there was still much ground to cover in the formation of the accepted atomic model. The next notable advancement in the field was made by Joseph John Thomson. Thomson was a successful scientist and mathematician, who has published thirteen books, and roughly two hundred papers in physics. His atomic breakthrough came during his studies of the cathode ray, in which he discovered the existence of electrons. In a series of experiments, Thomson used a magnetic field to see how a cathode ray (or beam of what is now known as electrons) would react in a vacuum. After several trials with different configurations and variables, Thomson was able to observe how these rays reacted, and could determine several things from this. The bending of the rays allowed Thomson to conclude that there are negatively charged particles smaller than an atom, and that atoms have no charge because they are electrically neutral. Based on these postulations, Thomson created his own model of the atom, dubbed the “plum-pudding” model, with negatively charged electrons dispersed throughout the positively charged atom. These extremely significant experiments allowed for this advancement in the atomic theory, earning JJ Thomson his place as a Cromulist Notable.

Now that the existence of electrons was generally accepted in the scientific community, the door was opened for others to discover the secrets of the atom. The next significant figure to do so was Ernest Rutherford with his famous gold-foil experiment. Prior to his revolutionary discovery at the atomic level, Rutherford was already a Nobel Prize-winning scientist in the field of chemistry. Three years after this feat which is often the epitome of a scientist’s career, Rutherford once more demonstrated his thirst for knowledge and desire to discover the unknown. He discovered the atom is mostly made of empty space, with a positively-charged nucleus at the centre, and electrons orbiting around this central region. This was found by bombarding gold foil with alpha particles (helium nuclei), and tracking how they either travelled through, or ricocheted/ bounced off the foil. It was found that an extremely high percentage of alpha particles travelled directly through, but surprisingly a few were deflected. This allowed Rutherford to postulate that atoms contained a dense nucleus, but further experiments conducted in different gases were required to allow him to prove that this nucleus was positively charged. This meant that negatively charged electrons had to orbit this nucleus. This limited knowledge is exactly what allowed for the next atomic breakthrough.

Niels Bohr, a scientist who had worked alongside both JJ Thomson and Ernest Rutherford found an issue with Rutherford’s model of the atom. Bohr hypothesized that the planetary model that his colleague had developed could not in fact be the true form of the atom, as the negatively charged electrons would simply be drawn into the positively charged nucleus, falling out of orbit and destroying the atom. Bohr could not accept this incongruity, and thus proposed a revised version of the model in which electrons travelled in orbits of fixed size and energy, with the energy of an electron dependent on the size of the orbit. This version of the atomic model would solve the issue of how the electrons would continue to orbit the atom. In order to have his postulate accepted by the scientific community, Bohr had to prove it through experiment. His experiment consisted of conducting spectroscopy on hydrogen gas. The data gathered demonstrated Hydrogen’s emission spectrum, characterized by separated coloured bands. These spaced bands of colour signified electromagnetic radiation being given off by the atom when it was bombarded with energy. This signified to Bohr that his theorized electron orbits had electrons moving between them when excited, and then emitting electromagnetic radiation in separate wavelengths (and thus colours) of light. The gaps between these coloured bands on Bohr’s spectroscopy reading marked the distinction between different orbits. Through his wit, dedication, and desire to discover, Niels Bohr embodies Cromulism in a way that only a Notable could. This new model of the atom that Bohr had just created was the saving grace for a struggling branch of inquiry, as it logically explained the very existence of these atoms.

Despite Bohr’s breakthrough, this was not the end of the journey of the atomic model. The next scientist to add the final subatomic building block was James Chadwick, who discovered the existence of a part of the atom that was not charged positively or negatively, so it was thus deemed the “neutron”. Like others before him, Chadwick had a postulation that he had to back up with experimental evidence. He theorized that large neutral particles existed in the nucleus of the atom, as he noticed a disparity between an element’s atomic number, and its atomic mass. This lead him to believe that there must be another subatomic aspect of each atom. To test his hypothesis, Bohr bombarded Beryllium with alpha particles, and observed the dislodging of unknown radiation from the Beryllium. It was later determined that this was not in fact radiation, but the very “neutrons” that Chadwick had hypothesized resided within the nuclei of atoms. Chadwick’s discovery is an extremely important step in the continuous improvement of the atomic model. Its significance earns Chadwick a spot among the Notables of Cromulism.

Since this significant advancement in the model of the atom, development of the theory has not ceased. Beyond the easily conceptualized Bohr model with Chadwick's neutron present, further quantum models have been developed to better represent the true nature of the atom. The quantum model, notably contributed to by Max Planck and Albert Einstein, involves a much more theoretical existence of the atom. In this model, the orbits that Bohr had theorized existed as cloud-like areas in which the electrons categorized in those orbitals were most likely to be found at any given time. The true location of these electrons within these electron clouds is unknown, only that there is a high probability of electrons presiding in their orbital. As the capabilities of human technology increase in the future, it is possible that the model of the atom will be subject to further change and advancement. The atomic model is one of the greatest accomplishments of humans, but it is far from complete. The journey for knowledge of the universe continues, and will be continued by Cromulists of the future, just like those who existed before them.