Executive Summary – Elementary Particles are those “things” that we believe are the fundamental building blocks of Atoms. All the research done so far begs the question: will it break down even further if we “bang on it hard enough” with a bigger, faster supercollider?
Gameplan: We will progress from Atoms down to “things” that are considered building blocks, and have been discovered at facilities such as the Large Hadron Collider at CERN.
We might say the study of Elementary Particles began with Democritus, who described his atoms as building blocks that moved around in a void and could collide or combine.
Our first modern discussion led to the words Compound and Element, with elements being the basic building blocks. The Periodic Table was developed and as more knowledge was gained, the word element would be replaced by the word Atom (and Molecule would replace Compound).
Studies of the atom led to the theory of a Nucleus surrounded by Electrons, with the nucleus containing protons and neutrons. We, at least for now, perceive the electron as being an elementary particle. If you find that you like electrons as you read more about them, you might enjoy the study of Chemistry, since electrons are responsible for holding molecules together and chemists love molecules. If you want to “dig down further” into the atom, you will probably like Physics.
Further work takes us to the Nucleus where we study those Protons and those Neutrons. These are comprised of Quarks and some other “stuff”. Quarks can be “up” or “down” with up having a charge of +2/3 and down having a charge of -1/3. Protons and Neutrons are called Baryons because they are composed of three quarks.
- A Proton is two up quarks and one down quarks. The charges sum to “+1”, thus explaining the positive charge we for protons.
- A Neutron is one up quark and two down quarks. The charges sum to “0”, thus explaining the neutral status of neutrons.
The above concerns the electrical charge. There is also a property called a “Color Charge” that has nothing to do with color as you perceive it in light (red- 650 nm, blue- 450 nm). It is used to provide distinction and the area of study is called Quantum Chromodynamics.
Forces between Quarks are mediated by Gluons. A gluon is an elementary particle that acts as the exchange particle (or gauge boson) for the strong force between quarks. Gluons have been described as carriers of the strong force that bind quarks together.
Finding or “Seeing” the Effect
Adding atoms to a molecule changes its mass, and this can show up on a Mass Spectrometer.
The effects of atoms, more specifically, the motions of the atoms in a molecule, can be observed as peaks on an Infrared Spectrograph.
The effect of electrons was observed in Crookes Tubes (https://en.wikipedia.org/wiki/Crookes_tube).
Evidence for Quarks was seen by physicists at the Stanford Linear Accelerator Center.
Timeline
- “Atomos” (Democritus) – around 400 B.C.
- Proton (Rutherford) – 1919
- Neutron (Chadwick) – 1932
- Quark – 1964
- Gluon – 1976
Rob Sterling 