Atoms are the smallest bits of matter in the universe. Here on Earth, there are 92 different varieties of naturally occurring atoms which display an array of physical elemental properties. There are also some man-made atoms on Earth as well, and there is a good possibility that in other parts of the universe these rare-Earth atoms exists in natural abundance. But all atoms are comprised of the very same fundamental components.
Atoms are comprised of three basic subatomic components. They are protons, neutrons and electrons. Protons and neutrons are found at the center or nucleus of the atom. Electrons orbit the nucleus of the atom at great distance and velocity.
Some people like to visualize atoms as little solar systems, but in reality this is not a true perception. The planets in orbit of the Sun are held there by gravity. The mass of an atom’s nucleus and of its electrons is so small that gravity, for all intensive purposes, is negligible or does not exist at the atomic level. Instead, it is the electromagnetic force which holds the components of atoms together. Actually, another way to look at this is that the electromagnetic force in atoms is so much stronger than any potential gravitational effect, the electromagnetic force totally dominates the atomic environment. Anyway, the contemporary scientific visualization of electrons orbiting an atoms nucleus is that of an electron cloud, as opposed to a more orderly assemblage of classical heliocentric orbital symmetry.
Protons are comprised of three even smaller subatomic particles called quarks; more precisely two up quarks and one down quark. While quarks are particles, they are really only quasi-particles in a transitional state between matter and energy. Protons exhibit a net positive electrical charge. The number of protons found in the nucleus of an atom determine its elemental properties and characteristics.
Electrons are elementary subatomic particles (meaning that they can not be divided into smaller constituent particles) which exhibit a negative electrical charge. Protons are 1,836 times more massive than electrons. Even though the mass of the electron is infinitesimally smaller than that of the proton, the net negative electrical charge of an electron is proportional to the net positive charge of the proton. Thus, electrically speaking, the electrical charges of an electron and a proton cancel each other out. Taking into account Einstein’s theory of special relativity, if the two particles exhibit the same but opposing electrical charges, but the electron’s mass is so much less than that of the proton, then electrons must be moving at a proportionally higher velocity to exhibit the same electrical energy. In fact, electrons travel through space at slightly less than the velocity of light.
Neutrons are subatomic particles formed when a single proton is united with a single electron. The electrical charges of the proton and electron cancel, and therefore the neutron has a net neutral electrical charge, hence the particles name. So why doesn’t every electron get together with a proton and form a neutron? Well, it takes a whole lot of energy to get a proton and electron in close enough proximity to each other to bond. While the number of protons and electrons in the atom determine its elemental properties, the number of neutrons establish the atoms isotope.
Protons, neutrons and electrons form stable atoms which exist for a very long time; billions of years. When neutrons are removed from the atoms nucleus they disintegrate into a proton and electron within about 15 minutes; that is, unless they are captured by another atom. When atoms are blown to bits in accelerators, they disintegrate into quarks, gluons, bosons, mesons, leptons, photons and other short lived particles which exist for millionths of a second in a quasi state between energy and matter. Even though these smaller particles are at least for a brief instant a form of matter, protons, neutrons, and electrons are considered to be the fundamental components of stable atoms.