You can’t see just one of them, but they are all around and in us. They are the smallest stable constructs of matter, and at the same time are little packages of energy. The idea for atoms dates back 25 centuries, when Ionian philosopher Democritus developed the very first theory of atomic structure. He hypothesized matter was made up of tiny particle Democritus termed “atomos,”in the Greek lexicon meaning indivisible.
Unfortunately, another Greek philosopher, born just fourteen years after Democritus died, took exception with his theories and proposed a few of this own. Many of Aristotle’s notions, as we know today, were whimsical absurdities. Unfortunately, almost 2,000 years past before Robert Boyle, experimenting with how atoms work, discovered that Democritus theory about atoms was pretty much correct. Today, Boyle is revered as the father of modern chemistry, and he defined many laws that are still respected as fundamental natural laws. But it would take another 200 years before scientists building on the efforts of Boyle and others who followed him, would discover just how atoms worked.
Early in the 20th century, Earnest Rutherford proposed a theory of atomic structure suggesting atoms had a nucleus of positively charged protons surrounded by a cloud of electrons. Furthermore, he proposed that the way atoms worked, was directly related to electrical interactions between the atoms elementary components. Danish Physicist Neils Bohr, building on Rutherford’s work, establish the electron shell theory, further refining how atoms electrically interact with other atoms. In 1932, James Chadwick discovered that Rutherford’s protons actually consisted of two types of nuclear particles, protons which exhibit a positive electrical charge, and neutrons, which are electrical charge neutral. The fundamental particle constituents of atoms all having been identified, physicist turned their attention to the relationships between these particles and transmutable status of energy and matter.
For the better part of the 20th century, physicists and chemists endeavored to understand the nano-universe of subatomic particles, attempting to establish a complete picture of how atoms work. They have done so with great success, but achievement of full understanding, with respect to quantum mechanical manifestations, remains elusive. Nevertheless, we can discuss with certainty today, the realities of the three major forces at work in atoms, the electro-weak force, the strong or nuclear force, and the electromagnetic force.
The electro-weak interaction, or force, is the weakest instance of energetic attribute within an atom. It is a force mediated by subatomic particles called “bosons,” and it is the exchange of bosons between an electron and a proton which form a neutron. Since protons carry a positive electrical charge and electrons a negative one, the electrical charges cancel out and the resulting particle has a neutral charge. Hence its name, “neutron.” In reality, neutrons are not an independent elementary particle, but a composite particle consisting of leptons(electrons) and a proton, held together by the weak force. When the week force disintegrates, the neutron releases a proton, which remains in the atoms nucleus, and an electron, which is expelled from the nucleus in a process called beta decay. When the number of neutrons in the atoms nucleus changes, a new isotope of the element is formed, exhibiting the same elemental physical properties, but different atomic properties.
The strong force involves the interaction of subatomic particles called gluons and quarks to form protons and neutrons. In this instance, gluons are thought of as force mediators and are also the force which hold protons and neutrons together in the atoms nucleus. The strong interaction, or force, is therefore also referred to as the nuclear force. While the strong force can be described and quantified, it has yet to be understood well enough to explain just how gluons work. It is a ongoing study which could be considered a search for the holy grail of particle physics. The heat of fusion (combining of deuterium and tritium atoms to form a helium atom) produced in the Sun or hydrogen bombs, and heat of fission (decomposition of uranium or plutonium atoms) associated with nuclear reactors and atomic bombs, are diametric examples of the strong force.
The electromagnetic force(EMF), is the result of opposing electrical charges; the positive charge exhibited by the protons in an atoms nucleus and negative charge exhibited by one or more electrons in orbit of the nucleus. EMF is hundreds of times stronger than the week interaction, but minute when compared to the strong nuclear force. Nevertheless, the electromagnetic force is the most prominent and visibly obvious atomic effect in the universe. It is responsible for the differentiation of physical properties of elements, as well as the electrical characteristics which define elemental interactions. It is the force which causes atoms to bond or clump together to form molecules and compounds, and may therefore be indirectly responsible for gravity.
Interestingly, gravity is a force or effect exhibited by atoms, but not a force at work within them. Gravitational effect is directly proportional to mass, and some elements, hydrogen and helium for example, have such slight atomic mass that even Earth’s gravity is not enough to hold onto them. Some scientists like to theorize, that like the other forces, gravity is an independent atomic force in its own right, represented in quantum mechanics by a particle called a graviton. Unfortunately, no intrinsic evidence has yet been discovered to substantiate the existence of such a particle, and no deficit of mass with respect to atomic structure has been identified representing its possible existence. It may well turn out to be a notion no less whimsical, than some of Aristotle’s.
What science has uncovered over the past 25 centuries about how atoms work, involves a mosaic of subatomic particles, and the three basic forces, weak, strong, and electromagnetic, all interacting to form stable atoms. There remains a whole lot, for upcoming generations of young scientists to learn and understand about how atoms work. Fortunately, they will have a great foundation of knowledge gleamed by past generations to consider and build on.
