Re: What are protons, nuetrons and electrons composed of?

Protons and neutrons are composed of three quarks each.
Quarks are elementary particles with fractional charges. Each proton has two up quarks with charges of 2/3 each and one down quark with -1/3 charge. Each neutron has two down quarks and one up quark (adds to zero, hence neutral, hence "neutron"). Electrons have not yet been found to have more structure within them. They are considered elementary.

Try visiting the following sites:

http://d0hs19.fnal.gov/newthesis/html/node3.html#SECTION00210000000000000000
http://www.astro.virginia.edu/~eww6n/physics/
http://physics.hallym.ca.kr/education/hep/adventure/scale.html