now let us study about ionization of atom
by electromagnetic radiation.
for an atom we can say, in an energy level
of an atom, we know that - total energy . of
an electron ,is negative, that we already
obtained that in any energy level the total
energy of electron is negative , this negative
energy we know it denotes boundness . when
the total energy of particle is negative it
means it is under the influence of an attractive
force or it is bounded with, some specific
boundries.
now in this situation as the electron is bounded
by the attraction of nucleus , we can state
that – when this energy . 
becomes zero . electron will be . free from.
nuclear attraction, obviously if the total
energy is 0 it means it will not be bounded
, we can state that - it is now free from
the attraction of nucleus .
like if we talk for hydrogen atom. in n equal
to 1 there is only 1 electron so energy of
electron we, define, we have already calculated
it is minus 13.6 electron volt , so here we
can say- if, 13.6 electron volt energy , here
we talk by a photon, is supplied . to hydrogen
atom. and say if this photon is absorbed by
the electron then we can say, total . electron
energy, becomes.
0, because its earlier energy was minus 13.6
e-v and we have supplied 13.6 e-v, so total
energy will be zero.
and here we can say, it will make , electron
– free, from atom and here we can say that
the atom is ionized, so here we can say, and
we can write that- the atom is, ionized , this
implies in this situation we can say that
this 13.6 electron volt energy is called.
binding energy.
or ionization energy- of electron, in n equal
to 1 of hydrogen atom. so in various situations
we can say - binding energy of an atom, or
binding energy of an electron. or ionization
energy of atom, is the amount of energy which
when supplied the electron will become free
from nuclear attraction, or the atom will
become ionized.
and here we can write f, or any , orbit . we
can state - mod of total energy of electron.
can be termed as , binding energy because
we know that total energy is negative and
if the same magnitude of positive energy is
supplied the electron will become free from,
the nuclear attraction and the same binding
energy we define as, ionization energy of-
atom. so you must, understand this phenomena
carefully as in various numerical , we will
need to understand the application of ionization
also .
