Magnetism
arises
from
two
types
of
motions
of
electrons
in
atoms
-
one
is
the
motion
of
the
____________________
in
an
orbit
around
the
nucleus
,
similar
to
the
motion
of
the
____________________
in
our
solar
system
around
the
sun
,
and
the
other
is
the
____________________
of
the
electrons
around
its
axis
,
analogous
to
the
rotation
of
the
Earth
about
its
own
____________________
.
The
orbital
and
the
spin
motion
independently
impart
a
magnetic
____________________
on
each
electron
causing
each
of
them
to
behave
as
a
____________________
magnet
.
The
magnetic
moment
of
a
magnet
is
defined
by
the
rotational
force
____________________
by
it
in
a
magnetic
field
of
unit
strength
acting
perpendicular
to
its
magnetic
axis
.
In
a
large
fraction
of
the
elements
,
the
magnetic
moment
of
the
electrons
____________________
out
because
of
the
Pauli
exclusion
____________________
,
which
states
that
each
electronic
orbit
can
be
occupied
by
only
two
electrons
of
opposite
spin
.
____________________
,
a
number
of
so
-
called
transition
metal
atoms
,
such
as
iron
,
cobalt
,
and
____________________
,
have
magnetic
moments
that
are
not
cancelled
;
these
elements
are
,
____________________
,
common
examples
of
magnetic
materials
.
In
these
transition
metal
elements
the
magnetic
moment
arises
only
from
the
spin
of
the
electrons
.
In
the
rare
earth
elements
(
that
begin
with
lanthanum
in
the
sixth
row
of
the
____________________
Table
of
Elements
)
,
____________________
,
the
effect
of
the
orbital
motion
of
the
electrons
is
not
cancelled
,
and
____________________
both
spin
and
orbital
motion
contribute
to
the
magnetic
moment
.
Examples
of
some
magnetic
rare
earth
elements
are
:
cerium
,
neodymium
,
samarium
,
and
europium
.
In
addition
to
metals
and
alloys
of
transition
and
rare
earth
elements
,
magnetic
moments
are
also
observed
in
a
wide
variety
of
chemical
compounds
involving
these
elements
.
Among
the
common
magnetic
compounds
are
the
metal
____________________
,
which
are
chemically
____________________
compositions
of
metals
with
oxygen
.
