CHEMISTRY
the ionicbond
ionic bonding is a type
of chemical bond
that
occurs
between two atoms when one atom transfers electrons to
another
usually happens between metals and non-metals
·
how does ionic
·
bonding work ?
O atoms and electrons
each atom has electrons that orbit the nucleus
arranged in
·
,
shells
atoms want to fill their outer/valence shell with electrons to reach the most stable / lowest-energy state they can (by satisfying the
·
octet rule
① formation ot ions
metals (like sodium) tend to have fewer electrons in their outer shell and tend to lose them. When they lose
·
an
electron.
they become a positively charged ion / cation .
non-metals (like chlorine) tend to have more
·
electron they become
,
a
electrons in their outer shell and tend to gain electrons When they gain
.
negatively charged ion/anion.
*
sodium chloride (Nack)
eg
*
Na
a) sodium atom
·
b)
*
+
:
::
11
·
in its outer shell
xxH
Chlorine atom
·
·
***
sodium (Na) has one electron
an
*
Chlorine (C1) has seven electrons in its outer shell
N
X
c) ionic bond formation
XX
::
·
* &
·
·
when sodium loses its electron , and chlorine gains that electron , they become ions
the
positively charged sodium ion (Nat)
and
negatively charged chlorine ion attract each other forming an ionic
,
bond (Nack)
the covalent bond
·
·
covalent bonding involves the sharing of electron pairs between atoms
typically occurs between non-metals and allows atoms to achieve full outer shells
how does covalent bonding work ?
① atoms and electron configuration
·
atoms aim to have a full valence shell which usually means 8 electrons (according to the octet
,
for
rule) , except for hydrogen and helium which aim
2
① single/double/triple bonds
·
·
single bond
=
double bond
:
one pair
of electrons is shared leg #2
two pairs of electrons are shared
-
.
H
leg O
.
-
H)
=
0
=
0
triple bond
·
=
three pairs of electrons shared leg (1 - N = N
.
eg water (H2O)
a) hydrogen atom
each hydrogen atom has
·
I electron and needs one more for
afull
outer shell
b) oxygen atom
oxygen has 6 electrons and needs [more:
·
it can share
1 electron with each hydrogen atom
⑧ D
c) overall structure
consists of two single covalent
·
gas tests
O
glowing splint test
a
·
H
H
HO
·
:
0
%
H
bonds"
test for oxygen (0 )
.
a
-
%
glowing splint (a wooden stick that has been burned and is still glowing) is inserted into a test tube
containing the gas
if oxygen is present the splint will reignite
·
,
② pop test
·
·
test for hydrogen (H)
a
-
a
lit splint is brought near the gas
if
hydrogen is present it will produce a characteristic "pop" sound
,
③ limewater test
-
a
test for carbon dioxide (CO)
bubble the gas through lime water (a dilute solution of calcium hydroxide) (Ca[OH]e)
·
(CaCOs)
if carbon dioxide is present the limewater will turn cloudy due to the formation of calcium carbonate
·
,
① blue litmus paper test
use
·
-
a test for chlorine
(((2)
damp blue litmus paper and place it in a container with the gas
if chlorine is present the blue litmus paper will turn red and may eventually bleach white
·
,
⑤ red litmus paper test
·
·
-
a
test for ammonia (NHs)
bring damp red litmus paper close to the gas
if ammonia is present the red litmus paper will turn blue
,
metal ion solutions O test for Calcium
·
·
·
reagent
=
(Ca2t)
Sodium hydroxide (NaOH)
add a few drops of sodium hydroxide to the solution hydroxide to the solution containing calcium ions
a
white precipitate of calcium hydroxide
Cal
+
2NaOH
-
(Ca[OH],) may form
CaCOH)c + I Nat