F. Lee Slick

This SMART website is hosted by the Illinois Institute of Technology

Ol' McDonald had a farm Ei Ei Ohh and on this farm he had elementary particles, with a Quark! Quark! here, and a Quark! Quark! there, here a Quark there a Quark, everywhere a Quark! Quark! Ol' McDonald had a farm, Ei Ei Ohhhh!


In the 5th century B. C. the Greek Philosopher Democritus proposed the idea of the atomas (meaning uncuttable or indivisible or not sliceable).  However his contemporaries ( Plato and Aristotle ) did not accept the idea of the atomas theory.  For over 2000 years this idea (atom theory) was lost.  Finally in1808 an English scientist and school teacher (John Dalton) formulated a precise definition of  the indivisible building blocks of matter that we now call atoms.

Summarized as follows:

1.  Elements are  composed of extremely small particles called atoms.  All atoms of a given element are identical, having the same size, mass, and chemical properties.  The atoms of one element are different from the atoms of all other elements.

2.  Compounds are composed of atoms of more than one element.  In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction ratio.

3.  A chemical reaction involves only the separation, combination, or rearrangement of atoms:  it does not result in their creation or destruction.  I other words matter can neither be created or destroyed. 

Therefore the atom is the basic unit of an element that can enter  into a chemical combination and it is the fundamental unit of matter.  However, it was noted after this that atoms actually possess an internal structure composed even particles which were called subatomic particles. In the 20th century scientists thought there were only three types of particles--electrons, neutrons, and protons.  None of these could be split into anything smaller.

Among those who contributed to these ideas were Joseph John Thomson   Nobel Prize  in Physics1906 discovery of the electron.  Robert Andrews Millikan  Nobel Prize in Physics 1923 charge of the electron.  Willhelem Konrad Rontgen Nobel Prize in Physics 1901 discovery of X-rays.  Antoine Henri Bacquerel Nobel Prize in Physics 1903 discovery radioactivity in uranium.  Marie (Marya Sklodowska) Curie and Pierre Curie  Nobel Prize in Physics 1911 worked on radioactivity. The proton was next on the list of building blocks or again these were thought to be the fundamental particles of matter.  Ernest Rutherford Nobel Prize in Physics 1908 investigation of the atomic nucleus.  Rutherford's associate was Johannes Hans Wilhelm Geiger  (Geiger counter) and Ernest Marsden graduate assistant.  Quotes from Rutherford:  "It was as incredible as if you had fired a 15-ich shell at a piece of tissue paper and it came back and hit you"  and to his students " all science is either called physics or stamp-collecting."  The neutron:  James Chadwick Nobel Prize in physics 1935 proof the existence of neutrons .

Mass and Charge of Subatomic Particles

              Charge                    Charge Unit


Mass (g)




9.10939 x 10-28

-1.6022 x 10-19



1.67262 x 10-24

+1.6022 x 10-19



1.67493 x 10-24



Discoveries in the early 20th century reveal that the atom was not the elementary particle, but that the electron, proton and neutron were now the elementary particles.  This theory soon fell apart beginning in 1937 many new particle resulted from the high-energy collisions between particles.  Today over 300 new particles are listed or catalogued.  There are much smaller particles out there and they are given the name of "quarks".  The term "quarks" was coined by Murray Gell-Mann and taken from the phrase "Three quarks for Muster Mark"  by James Joyce's  from the novel Finnegans Wake.  It is thought that there are 6 particles called "quarks" with the name of "up", "down", "strange", "charmed", "bottom:", and "top,"



Mass (GeV/e2)

Electric charge(e)

























First theory or model required three varieties, or "Flavors" of quark referring to the Baryons.   Antibaryons  consist of three antiquarks, and Mesons consist of one quark and one antiquark, giving them a baryon number of 0, as required.  An objection to this model was the existence of hadrons composed of the same flavor quarks which violated the Pauli Exclusion Principle..  Each quark carried three colors charges, they were different but almost the same so the Pauli Exclusion Principle did not have a problem with them. These new particles were very unstable and had very short life half-lives, mainly on the order of 10-6 s to 10-23 s.   However scientists came to realize that these particles were the elementary particles they were seeking.  Quarks are the smallest known building blocks of matter, they never occur alone and are always found in combination with other quarks in larger particles. At present these appear to be the building blocks of the matter that is in the Universe.  In conclusion Ol' McDonald had a farm with a Quark! Quark! EVERYWHERE!!!!!!!!!!   (Standard model of particle physics shown below.) For a list of particles click on the following: http://www.wordiq.com/definition/List_of_particles.  My favorite particle is the "Oh_My_God" particle, what a name, this is an extremely high_energy photon.  No isolated quark has ever been observed.  The force between quarks has been described by one author as follows:  (Harald Fritzsch, Quarks, The Stuff of Matter, London: Allen Lane, 1983)   Quarks are slaves of their own color charge...bound like prisoners of a chain gang....Any locksmith can break the chain between two prisoners, but no locksmith is expert enough to break the gluon chains between quarks.  Quarks remain slaves forever.

Check out the following website:  http://www2.slac.stanford.edu/VVC/theory/quarks.html.


Chemistry Raymond Chang McGraw-Hill Higher Education 2002
College Physics 7th Edition Sears/Zewansky/Young Addision Wesley 1991
College Physics 6th Edition Serway/Faughn Thomson (Brooks/Cole) 2003
Physics Principles and Problems Merrill (Ziyzewity/Neff) Glencoe McMillian/McGraw Hill 1992 

Back to the SMART index page.

Last update 08/06/04