Briefly explain the elementary particles of nature.

Explanation

(i) An atom has a nucleus surrounded by electrons and nuclei is made up of protons electrons and nuclei is made up of protons and neutrons.
(ii) Till 1960s, it was through that protons, neutrons and electrons are fundamental building blocks of matter.
(iii) In 1964, physicist Murray Gellman and George Zweig theoretically proposed that protons and neutrons are not fundamental particles, in fact they are made up of quarks.
(iv) These quarks are now considered elementary particles of nature.
(v) Electrons are fundamental or elementary particles because they are not made up of anything.
(vi) In the year 1968, the quarks were discovered experimentally by Stanford Linear Accelerator Center (SLAC), USA.
(vii) There are six quarks namely, up, down, charm, strange, top and bottom and their antiparticles.
(viii) All these quarks have fractional charges. For example, charge of up quark is `+2/3`e and that of down quark is `1/3`e.
(ix) According to quark model, proton is made up of two up quarks and one down quark and neutron is made up of one up quark and two down quarks.
(x) The study of elementary particles is called particle physics and it is an active area of research even now.