When
two
negative
ions
get
close
to
each
other
,
they
____________________
.
When
a
positive
and
a
negative
ion
get
close
to
each
other
,
they
____________________
.
The
positive
ion
will
be
formed
from
an
atom
that
has
a
tendency
to
____________________
electrons
and
will
usually
be
a
____________________
.
A
negative
ion
will
be
formed
from
an
atom
that
has
a
tendency
to
____________________
electrons
and
will
usually
be
a
____________________
.
Metals
and
nonmetals
can
bond
together
by
forming
an
____________________
bond
.
____________________
atoms
have
a
strong
attraction
for
electrons
.
A
chlorine
atom
can
take
____________________
electron
from
a
sodium
atom
.
When
2
ions
are
held
together
by
the
____________________
between
the
opposite
charges
,
this
is
called
an
____________________
bond
.
Chlorine
is
a
gas
made
up
of
atoms
found
in
____________________
,
and
has
the
formula
Cl2
.
Sodium
exists
as
a
____________________
made
of
____________________
atom
(
s
)
Each
chlorine
atom
in
the
Cl2
molecule
needs
____________________
sodium
atom
to
react
with
.
Since
there
is
one
sodium
ion
for
every
chloride
ion
,
the
ions
are
in
a
____________________
:
____________________
ratio
.
The
formula
is
then
written
as
____________________
.
Since
there
are
____________________
calcium
ions
to
____________________
fluoride
ions
,
this
reduces
to
a
1
:
2
ratio
and
the
formula
for
calcium
fluoride
is
CaF
2
