Subatomic Particles The poet, too, is not nearly so concerned with describing facts as with creating images and establishing mental connections. - Niels Bohr

The Original Three  The three subatomic particles that are the most familiar are the protons, neutrons and electrons.

Parts of parts  In the late 1960s scientists discovered protons and neutrons themselves were composite particles.  they were the result of combining still smaller particles known as quarks.

Elementary and Composite Particles  Elementary particles are like electrons and quarks  Composite particles are like protons and neutrons.  Elementary particles have no substructure and no smaller constituent parts

Charged particles  one of the most basic properties of electrons, protons, and neutrons is their charge.  Electrons are negative, protons are positive, and neutrons are neutral.  It's the attractive electromagnetic force between protons and electrons that holds atoms together.  it's the different charges of various ions that causes atoms to combine into molecules.  The picture shows a network of sodium ions (purple) and chlorine ions (orange).

Quarks  Protons and neutrons are made up of different combinations of quarks.  Quarks are one of the three major groups of known elementary particles.  There are six types, or flavors, of quarks, half of which are up-type quarks with a positive charge and the other half are down- type quarks with a negative charge.  Here's the list of the flavors and their charges: up, charm, and top quarks are +2/3, while down, strange, and bottom quarks are -1/3

The Nature of Quarks  Quarks don't exist independently in nature - they're always found combined with one or two other quarks.  These combinations of quarks are held together by the strong nuclear force and are collectively known as hadrons,  Hadrons make up the vast majority of composite particles, and both protons and neutrons are hadrons.

Protons and Neutrons  A proton is made up of two up quarks and one down quark, which gives it its +1 charge (since 2/3 + 2/3 - 1/3 = 1). Neutrons have the opposite structure, which is one up quark and two down quarks, which makes for a neutral charge (2/3 - 1/3 - 1/3 = 0)

Hadron  Any hadron that is made up of three quarks is known as a baryon.

Leptons  Electrons are the best known members of another major group of elementary particles, the leptons.  Just like quarks, there are six flavors of leptons.  These flavors can be divided into three generations, with each successive generation much more massive than the one before it.

Stability  up and down quarks are the lightest, then charm and strange, then top and bottom.  Only the lightest leptons and quarks are stable.  This is why up and down quarks form protons and neutrons.  it's also why electrons are found in atoms and not their heavier counterparts.

The Neutrino  There are six flavors of leptons.  You already know the electron, and you may have heard of the other member of its generation, the neutrino.  The neutrino - or, more accurately, the electron neutrino - is a nearly massless particle.  It was first proposed by Wolfgang Pauli in 1930 to account for the slight loss of total energy and momentum in a process known as beta decay.  This is a process in which a neutron decays into an electron, a proton, and a neutrino

Fitting it all together