Composition of Nucleus
The composition
of a nucleus is normally described as following terms and symbols
Z - Atomic number = number of protons
N - Neutron
number = number of neutrons
A - Mass number
= Z + N = total number of protons and neutrons
Both
the proton and neutron are also known as nucleon. Thus the number of nucleons
in an atom is A. Nuclear species are shown by the notation AZX
where X is the chemical symbol of the species.
Size of the Nucleus
It has
been found that a nucleus of mass number A has a
radius R = R0A1/3 where
R0 = 1.2
× 10–15 m. This means the volume of the nucleus, which is
proportional to R3 is
proportional to A.
Thus
the density of nucleus is a constant, independent of A,
for all nuclei. Different nuclei are likes drop of liquid of
constant density. The density of nuclear matter is approximately 2.3 × 1017
kg m–3.
