.
.
F. Soso - CERN 1998
.
The Periodic System of Elementary Particles
Electric charge
QUARKS
.
LEPTONS
Electric charge
( strong nuclear force)
( no strong nuclear force)
+ 2/3
   u
c
t
ne
nm
nt
0
.
"Up" 
"Charm"
"Truth"
E-neutrino
Mu-neutrino
Tau-neutrino
.
- 1/3
d
s
b
e-
m-
t-
- 1
.
"Down"
"Strange"
"Beauty"
"Electron"
"Muon"
"Tau"
.
.
Protons and neutrons (atomic nuclei) are made of quarks:   
Proton = (u-u-d),  Neutron = (u-d-d)
The stable particles, found in ordinary matter, are only a few :      
u, d, e-, some neutrinos
All other, heavier particles decay into the stable ones.