Values at the atomic and subatomic levels



Dear Friend:

Matter is made up of Molecules.

Molecules are made up of Atoms.

Atoms are made up of Nucleus and surrounding Electrons.

Nucleus is made up of Neutrons and Protons. Protons are made up of Neutrons and Positrons.

Neutrons are made up of Quarks.

Quarks are thought to be made up of Pre-quarks.

At present Quarks are fundamental particles that are constituents of neutrons and protons.

There are six different type of quarks.


Flavor (Type) Mass


Electric Charge


u up 0.004 +2/3
d down 0.008 -1/3
c charm 1.5 +2/3
s strange 0.15 -1/3
t top 176 +2/3
b bottom 4.7 -1/3


In particle physics mass of a particle is not measured in grams, instead it is measured in unit of energy.

Because energy is related to mass by an equation E=mc.

One eV (electron Volt) is the amount of energy that an electron gains when it moves through a potential difference of 1 Volt ( in a vacuum).

G stands for Giga. Giga means 109 (10 to the power of 9).

1 GeV is a billion electron Volts.


Mass of a Neutron is 0.940 GeV


Mass of a Proton is 0.938 GeV


Mass of an Electron is 0.511 MeV (Mev = Mega or million electron Volts)


Baryons (qqq) and Anti-baryons (qqq)
Symbol Name Quarks Electric Charge Mass (GeV/c) Spin
p proton uud 1 0.938 1/2
n neutron udd 0 0.940 1/2
Λ lambda uds 0 1.116 1/2
Ω omega sss -1 1.672 3/2
p anti-proton uud -1 0.938 1/2


Hadrons are particles made from quarks and /or gluons, bound together by their strong interactions.

There are two classes of hadrons: baryons and mesons.

Baryons are particles made from a basic structure of three quarks.

For example, proton's basic structure is two up quarks and one down quark.

A neutron's basic structure is two down quarks and one up quarks.

Proton is the only baryon that is stable in isolation.

Ferminos are particles characterized by spin in odd half integer quantum units (1/2, 3/2, 5/2,..). ( Named for Italian physicist Enrico Fermi).

Ferminos obey the Pauli Exclusion Principle rules.

Quarks, Leptons, and Baryons are all ferminos.

Electrons, muon, and tau are leptons.

Bosons are particles with a spin of an integer number (0, 1, or 2,..) of quantum units of angular momentum. (Named for Indian physicist S. N. Bose).

Carrier particles of all interactions are bosons.

Mesons are also bosons because mesons have integer or zero units of spin.

Mesons do not obey the Pauli Exclusion Principle rules.


Mesons (qq)
Symbol Name Quarks Electric Charge Mass (GeV/c) Spin
π+ pion ud +1 0.140 0
Κ- kaon su -1 0.494 0
ρ+ rho ud +1 0.770 1
D+ D+ cd +1 1.869 0
ηc eta-c cc 0 2.979 0


The size of an atom is 10-11 meter.

The diameter of it's nucleus is about 10-15 meter.

Rest is space.