Protons and neutrons are no longer the smallest known particles. There is the Standard Model of Particle Physics- the most complete theory of the smallest particle we have now. In this theory, it deals with three groups of particle – quarks, leptons and bosons. But, what are quarks?
Quarks are one of the most elementary particles we have known so far. There are six types of quarks – up quark, down quark, charm quark, strange quark, top quark and bottom quark. From up quark to top quark and from down quark to bottom quark, the mass increases in ascending order.
All the quarks in the top group i.e. up quark, charm quark, top quark have a charge of +2/3 e. You might have learnt in school that the charge of an electron is the smallest known electrical charge. But, now the smallest electron charge we know is the charge of down quark, strange quark and bottom quark which all have a charge of -1/3 e.
Quarks makes up of protons and neutrons. A proton consists of two up quarks and one down quark while a neutron consists of one up quark and two down quarks. So, two up quarks and one down quark = 4/3 e – 1/3 e = e and this is why proton has 1e. And for neutrons you do yourself.
Knowledge Glutton 
The smallest thing we have ever been discovered is the strings (string theory)inside these subatomic particle . isn’t?
LikeLike
Yes & No because in theoretical physics, yes strings are the smallest things but they have been observed or detected. Even the theory is still up for debate. But these quarks have all been observed and studied on the particle colliders like LHC or RHIC.
LikeLike
Draw all four order diagrams of Quantum Electrodynamics (QED) process of pair
annihilation.
LikeLike
I will do in another blog
LikeLike
A couple of typos, I think.
“From up quark to top quark and from bottom quark to bottom quark, the mass increases in ascending order.”
Should that be “…from down quark to bottom quark,…”?
Also:
“Quarks are made up of protons and neutrons.”
Do you mean:
“Quarks make up protons and neutrons.”
Or maybe:
“Protons and neutrons are made up of quarks.”
LikeLike
My bad, you are correct. Just a typing mistake, sorry by the way.
LikeLike
Please the article again. I have corrected it.
LikeLike