The Basic Structure of an Atom - Structure of Atom Video Lecture - Class 9

structure of an atom an atom is the
smallest particle of matter that has
independent existence it is too small to
be viewed even under a powerful
microscope to understand the structure
of an atom we can visualize an atom as a
sphere
the atom has two major divisions in the
center of the atom there is a nucleus
the size of the nucleus is extremely
small compared to the size of the atom
observe that the nucleus consists of two
types of particles known as protons and
neutrons
the electrons revolve around the nucleus
in fixed orbits these are the electron
shells
the space around the nucleus in which
the electrons revolve determines the
size of the atom there's an atom
consists of three elementary particles
namely proton Neutron and electron atoms
of different elements are built up from
different numbers of these fundamental
particles shown here are a few examples
if an atom has one proton and one
electron it forms an atom of hydrogen
but if the number of protons electrons
and neutrons are eight each then we have
an atom of oxygen
if 11 protons 11 electrons and 12
neutrons are present in an atom it forms
an atom of sodium
the electrons are not found scattered
around the nucleus they are arranged in
different shells around the nucleus as
seen here each orbit is associated with
a definite amount of energy and is
therefore called energy shell or energy
level these energy levels are numbered
starting from nucleus outward as 1 2 3 4
and so on are named as k l m n so on the
maximum number of electrons that can be
present in a shell is given by the 2 n
square rule where n is the number of the
shell the filling up of electrons in
different shells during the 2 n square
rule may be understood from the table
shown here