dear students lets start with the topic of
nuclear physics and very first thing we’ll study in nuclear physics is composition and
structure of nucleus. the discovery of nucleus you can recall it was done by ruther ford,
in his alpha scattering experiment. it was, in year 19 11. when. this ruther ford’s.
alpha scattering experiment. was performed. and this was the discovery of nucleus. in
which it was found that majority of mass and charge of an positive charge of an atom is
concentrated at the centre. and positive charge is in, form of protons. and later in 19 32.
there was several experiments, which were performed by jame chadwick. neutrons were
discovered, it was discovered that neutral particle exist inside a nuclear which are
called neutrons. so this was the discovery of. neutrons. in nucleus. so the approximate
structure. of nucleus was assessed that inside the nucleus there are 2 kind of particles.
which are protons and neutrons protons are. positively charged. and. neutrons are electrically,
neutral. and electrons on nomenclatures and conventions were made for. mathematically
representing a nucleus. like, in a nucleus. total number of protons. were given a specific
terminological name which is called atomic number. of element for which. the nucleus
we are talking about and it was denoted by z. and. total nucleons. nucleons are basically
the constituent of nucleus these are protons plus neutrons. these were given specific number
which will be given. the name mass number of element. which was denoted by later ay.
and. notation used. for an element. x was, with the symbol of element. we can write,
in subscript the atomic number which gives us a number of proton and in super script
either right side or left side symbol, the mass number of the element so. in a way. an
element with its, nucleon quantity is represented as z x ay where z is the atomic number of
element. and this also called. charge number. because this gives us the idea about total
amount of positive charge particles within nucleus. and here this ay, is also termed
as, mass number. because this giving us the total number of particles within the nucleus.
in the similar notation we can also. denote, some elementary particles like if we talk
about protons. protons are represented by, the symbol p. with charge number 1 and mass
number 1. similarly we talk about neutron. neutrons are represented by the later n. with
a charge number zero and mass number 1 because there are no charges with neutrons. similarly
we talk about electrons then. in case of electrons the mass is approximately, zero or the mass
of electrons negligible compare to proton neutron so we consider its mass number to
be zero. and charge number to be, minus 1, so this is the way how the basic elementary
particles are represented on paper.