m o lecu
if
covalellt b0ftd
Fitd.D
?.8 E6eniia!
Co)t Atah,gl,
rTJe-
tq
i*nic brlrd
2A84 cartand Scinnr€!
Name
Teacher
Regents Chemistry
-1-
Covalent Bonds
Definition:
Types of Covalent Bonds
A. Nonpolar Covalent:
B. Polar Covalent
-2-
C. Coordinate Covalent
Properties of Covalent Bonds
-3-
WS Covalent Lewis Dot Structures
What is the duet rule? Which atom does this apply to?
What is the octet rule?
Draw the electron dot (Lewis) structures for each covalent molecule.
F2
02
HzS
Coz
HCI
NH:
Hz
Nz
PCl3
siH4
BeCl2
BHs
(
Which molecules above are exceptions to the octet rule
-4-
GVATE$€T ts#ruffiBN:G
shore electrons, ottempting to
lovolent bonding occurs when two or more nonmetols For excmple:
iiofn o stoble ocltet of electrons of leost pori of the time.
Fi' + 'Cll
I
I
._+,qrg)
Note thot hydrogen
is content wlth 2,
not 8, electrons.
palrs of
Show how covolenl bonding occurs tn eoch of the followlng
shcre one, two or fhree poirs of electrons.
atoms' Atoms may
I
I
l
ffir
2. F+F(Fr)
3, O+O(Or)
T
4. N+N(Nr)
"5, C + O (CO2)
6. H+O(H2O)
Chemktry
tFB766
dnstructlonol
Folr, lnc,
Ele
Sr
2.
3H13'
g. co,
CH3OH
9.
N2
10. NlI3
3. F{Je
OF,
11. HCN
5.
HzS
12. HCIO
6.
PC13
t3.
7.
SiOz
14. c2H2
4_
&n
$
-6-
c2H4
ghegi?istr{:
Name
Form WS4.1.4A
PerfoO
Date
BONDING
eaval,srYt fitqrl;d,s
are attracted
Covalent bonds are bonds formed by sharing electrons. The electrons ofone atom
from the
electron
an
remove
to
enough
pulls
strongly
to the protons of another, but neithei atom
is less
elements
the
between
difference
other. Covalent bonds form when the electronegativity
hydrogen
when
or
Table)
Periodic
the
of
than 1.7 (see the Electronegativity table on the back
rather,
behaves like a metal. When a covalent bond forms, no valence electrons are transferred,
and
equally
are
shared
electrons
the
they are shared. Ifthe electronegativity difference is zero,
1.7,
the
than
less
but
0.4
greater
than
is
the bond is nonpolar. If the election.gitiuity difference
is
bond
the
and
(nonrnetal)
element
electrons are displaced towards the more electronegative
atoms
the
that
a
way
such
in
pair
up
a covaient bond, unpaired valence electrons
polar. In
complete their outer shells.
molecular orbitals form'
Electron Dot Diagrams showing unpaired Valence Electrons (Norrz when bonding occurs'
separate orbitals)
into
move
orbital
energy
lowest
in
the
p"ir"O
no.tn."lty
a result, the two electrons that are
Li' Be' B
,
F,
C
,Ne,
Pairins Electrons:
Nonpolar Covalent Bond: Clo + Clo + Clz
Polar Covalent Bond: H* + Cl-
+
HCl
:cl
.+'Cl : -) :cl:cl:
H. +'Cl:
+
H:Cl:
Based on your understanding of covalent bonds, answer the questions below'
1.
Draw electron dot diagrams for hydrogen and oxygen'
Z.
oxygen' Al1 outer
Draw electron dot diagrams showing the pairing of electrons to form water from hydrogen and
shells should be comPlete.
3.
Are the bonds in water polar or nonpolar. How do you know?
@ Evan P.
Silberstein,2002
-7-
a)
€.)
3/
cJcO/
d)
|
=ITE\
ol\
a
I
()
tt,
;z--r
iFz
H
z5
= '?-*
I
L
Eto
d)
&
{t
li
+)
h
>5
aa)
q)
O
ftf
EEZ
oct
H
+i
ac.l
ts
g
c)
d
c.-.
P
fr
cs
o
(n
I
()
q;
4)
o
o
C)
d
qr
()
6d
a
()
(t)
0)
t)H
tDi4nri
Fllv+i
elrr
o_Fqf
i?Ti' A J u_,!_e
t\
L)l"
m
t-L!u4
I
e)
ah
€
z
d)
o
o
-o
H
lJr
x
;
z
4
4)
Cd
0
c.l
*'d
sf
HN
cn(J
\J
lri
m
i4r
O
H
F)
).1
U
z
Q
-8-
SHApE$ GF MSLFCU1
FS
Nome
Uslng VSEPR Theory, nqme ond sketch the shope of the followlng molecules.
rr
7, HF
N2
2, HrO
8,
CH3OH
cq
9'
HrS
I
,
3.
t
4, NH.
10.
5.
I
CH,
6. so.
)hemtstry IFBT66
l.
12
cHcl3
12. 02
41
@lnstructlonol Foir, lnc.
-9-
Nome
PCILARf,W @F MCg.EEUffiS
ffi-
H
)etermine whether the following rnolecules o re polor or nonpolcr,
l'
N2
7, HF
2.
Hro
B,
CH3OH
3.
CO,
9'
HrS
4,
NH,
10,
g{
Ac !'r
12
t,
4
6,
,5.
CHo
1
t.
cHcl3
8,
lt,
14,
6.
SO,
12, 02
15,
*
16,
p
17.
Chemistry
1F8766
ffiicner
C,h.etnisb'ral: FOrm Vfs4 .
1.
Name
6A
R'c.
Perrod
Date
BONDING
cog$i<i$g Palar lvfol#cvls.
s
difference
To determine if a compound is polar, you must consider the electronegativity
th!
electronegatlvitV
If
compound.
the
flti
within each bond and the three dimensional shape of
polar' Electronegativity -difference is greater than 1.7 or close to zefo,th" "ompound is not
differences around
differences above i.7 are found in ionic compounds' Electronegativity
differences between 0'4
zero are found in molecules with nonpolar bonds. Electronegativity
be polar or nonpolar
can
andl.l are found in molecules with polar bonds. These molecules
Molecules with polar bonds distributed symmetrically are
depending on their shapes.
polar' An irnaginary
nonpolar.'Asymmetricaimolecules with polar bonds are polar. Water is
the negative
line can be drawn through a water molecule separating the positive-pole.from
n1T:]1
Oioxifej1
pole. This is because th"""hurg", are distributedasymrnetrically' Carbon
carbon'
the
around
t"ruur. the electronegative oxygens are distributed symmetrically
(o:c=o)
"
Water
''
O :
o*
H
,
because the charges-are
is potar,'asymmetrically,
lliiiiui,t'ro
The
:iX'J:'Xf"i'Ji.|t1['3?l:,,?::,:nu'n'o'o
Determine if each of the compounds listed below, I0NIC, POLAR, or
to determine the shape'
follows: [1] determine the types of bonds. [2] draw electron dot diagrams
NONPOLAR as
Type of
Bond:
Compound
IoNIc,
PoLARo or
NoNPOLAR
HCI
CHo
Electron Dot
Diagram
Type of
Bond:
Type of
Compound
: IONIC,
Compound
IONIC,
PoLAR, or
NoNPoLAR
POLAR, or
NONPOLAR
cc14
cH3cl
Cl"
N2
KBr
H,S
NH,t
NaBr
O Evan P. Silberstein,2007
-1 1-
Electron Dot
Diagram
Type of
Compound
: IONIC,
PoLAR, or
NoNPOLAR
BAN DIHYDROGEN MONOXIDE!
and kills uncounted thousands of
Dihydrogen monoxide is coiorless, oJott"tt, tasteless,
inhalation of DHMO' but the
people every year. Most of these deaths-are caused ty accidental
'a*g"tt
of dihydrogen monoxide do not end there'
of DHMO
to its solid form causes severe tissue damage' Symptoms
Prolonged
""ptt*"
a1d possibly a bloated feeling' nausea'
ingestion can include excessive sweating and urinatiol
become dependent' DHMO
vomiting and body electrolyte imbalancl. For those who have
withdrawai means certain death'
Dihydrogen monoxide:
. is also known as hydroxl acid, and is the major component of acid rain'
' contributes to the "greenhouse effect'"
' may cause sevefe burns'
."o''t'ibutestotheerosionofournaturallandscape.
.acceleratescorrosionandrustingofmanymetals'
. *uy .u.rse electrical failures und d".r.used effectiveness of automobile
brakes.
. has been found in excised tumors of terminal cancer patients.
Contamination is reaching epidemic proportions!
('-
have been found in almost every stfeam, lake, and
Quantities of dihydrogen monoxide
g:ut the pollotion is global, and the contaminant has even been found
reservoir in America i"d"y
damage in the midwest, and
in Antarctic ice. DHMO has caused miilions of Jolars of property
recently California.
Despite the danger, dihydrogen monoxide is often used:
' as an industrial solvent and coolant'
' in nuclear Power Plants'
' in the Production of stYrofoam'
' as a fire retardant'
' in many forms of cruel animal research'
' in the distribution of pesticides'
. as an additive in certain "junk-foods" and other food products.
chemical'
Even after washing, produce remains contaminated by this
nothing can be done to
Companies dump waste DHMO into rivers and the ocean, and
wildlife is extreme, and we cannot
stop them because this practice is still legal. The impact on
afford to ignore it anY longer!
distribution,,or{se of this
The Ameri.un gou-"*-ent has refused to ban the production,
of this nation'" In fact, the
damaging chemical auE to its "importance to the economic health
DHMO, and designing
navy and other militar y organizalions arb conducting experiments with
Hundreds of
multi-billion dollar devices to control and utilize it during warfare situations.
underground
military research facilities receive tons of it through a highly sophisticated
distribution network. Many store large quantities for later use.
-12-
Chemistry Regents
Name
\
AIM: Writing chiilpical formulas for molecular compounds.
\
\
Problems:
Guidelines:
1) Nitrogen trifluoride
2)
Carbon monoxide
3)
carbontetrafluoride
4) tefaphorous decaoxide
5)
sulfur hexafluoride
6)
dihydrogen monoxide
7) dinitrogen tetrahydride
8) nitrogen
9)
1
trihydride
nitrogen monoxide
0) Dinitro gen monoxide
11)sultur dioxide
-1 3-
Naming Chemical ComPounds #1
Directions: Write
each compound in the space provided'
1.
Sodium sulfide
2.
Magnesium chloride
-1 .
Ammonium fluoride
4.
Sodium acetate
5.
Silver bromide
6.
Calcium oxide
7.
Potassium oxide
8.
Calcium nitrate
9.
Lithium sulfate
i0.
Potassium phosphate
11.
Potassium hydroxide
t2.
Magnesium chlorate
-14-
13.
Iron(II) nitrate
14.
Carbon monoxide
15.
Sulfir dioxide
16.
Iron(III) nitrate
t7.
Carbon dioxide
18.
Sulfur trioxide
19.
Lead(II) oxide
20.
Lead(IV) oxide
2t.
sb(oH)3
22.
sb(oH)s
z-'t.
Coz(SO+)r
24.
CoSO+
-1
5-
C'ltemisb'r!: Form WS4 . 3. 4A
Period
BONDING
ttlan;rt g binarej C.'avalsnb 9an1avrrds
negative
Nonmetals are two-faced elements! Although they normally have
oxidation
positive
oxidation states, nonmetals can behave like metals and have
when two
states. As a result, two nonmetals can combine to form compounds.
low-er
nonmetals combine, they form covalent bonds. The nonmetal with the
state'
In
electronegativity behaves like a metal and has a positive oxidation
behaves
carbon dioxide (COr), the carbon behave like a metal while the oxygen
The
formula.
the
and
name
the
in
first
is
written
metal
like a nonmetal. The
C*a:
carbon,
(C:
element
the
of
name
the
as
same
name of the metal is the
atoms is
carbon). If there is more than one atom of the metal, the number of
is
written
nonmetal
The
below.)
prefixes
of
list
(See
the
prefix.
indicated with a
(
\
Why are
you so
negative?
)
i
Why are
you so
positive?
the name
last in the name and formula..The name of the nonmetal is the same as
O-' =
(O
oxygen,
=
plus
IDE
two,
or
syllable
final
of the element minus the
(even
when
prefix
a
with
indicated
is
atoms
oxide).The number of nonmetal
the
because
easy,
is
compounds
these
for
formulas
there is only one). Writing
prefi4
lgllllbg
Jubscri
Examples
dichlorine trioxide
silicon tetrafluoride : SiFo
Number of Atoms
ClrO, :
1
mono
2
di
tri
Name the following binary covalent compounds'
1
Pro, "'"
4.
AsrP,
4
tetra
A
penta
b
hexa
7
hepta
U
o
octa
u
n0na
10
deca
5. IFr.......
6.
SeS,
7.
SO,
.....
......
8. CO ......
9.
10.
SBru.....
Nrot
Prefix
" "'
O Evan P. Silberstein,2002
-16-
Name
th€1i?istrg': Form ws4.3 .2
Date
BONDING
Aianing
M,or
Perloo
e eoxryourrd,s
Write ttre correct name of the
formulas listed be1ow.
comPound
on the space provided for each of the
31. KCl
32. MgI,
33. NaHSO4
34. Hg.(POr),
35. Ni (CI03)2
36. CdF2
31. SnS
38. CO,
39. NaCl
40. sb (No2)3
4L. Sn(CO3)2
42. KHSO4
43. AsI3
44. NH4OH
45. SiCI4
46. NH4CrO3
47 . Cr2(C2oa) s
48. NiF2
49. SO,
50. Bico3
5L. As2O,
52. CdO2
53. (NHr)rCrro'
54. KCIO3
55. SO:
56. Zn (No:)z
57. C.Pn
58. SnOt
59. NH.Br
60. NarO
1. Ca3(POa)z
2. Pbr4
3. Al (HSO4)3
4. Fe (0H).
5. CI,
6. CsrSOn
1. LiHCO3
8. BaSOn
9. AIP
10. NH4NO3
11. Curo
L2. HgrCO.
13. AqrCrOn
L4. Cu(SCN),
15. LiOH
16. AgzS
L7. Rb3N
18. FeSOn
19. ZnBr2
20. Pb (CrOn),
2L. MnCrrOt
22. SrH,
23. Sr (CH3CoO),
24. CS,
25. MnO,
26. K.P
27 . NarSrO,
28. BaS
29. H3PO3
30. FrMnOn
@ Evan P.
Silberstein,2002
-17 -
Nqme
IONEC VS" COVATENT BGroNS
ffi
rA/hen nonmetqls chemicolly bond they do so by shoring electrons. The bond is colled o
bond, When on octive metoi qnd o nonmetol bond, the octive metol tronsfers
,uoiunt
one or more electrons to the nonmetol, This bond is colled on ionic bond. lonic
compounds (except for boses) are qlso colled solts.
clossify the following compounds os ionic or covalent,
l.
14,
N2
2. co,
15,
NoOH
3' Hro
16,
NO,
4.
BoSOo
17, AIPO4
5'
02
18,
FeCl,
6.
NqF
19,
Prou
7.
NorCO.
20.
NrO.
B.
S^
21.
H2
SO,
22,
qo
LiBr
23,
KI
MgO
24.
P4
Fr
10,
I
CoCl,
l,
6
12. c2H5oH
25, CHo
13.
26,
HCI
NoCl
Dr,gw on electron shell diogrom of the
Drow on electron shell diogrom of the
lonic compcund colcium oxide, CoO,
covolent compound methone,
Blologry |FB76S
CHo,
dnstrucilonol Foir, lnc.
Chemical Bonds
Form Ls4 . 14
Ohsr?istr9:
D:^a
! qYv
BONDING
i -- Answer the questions below by circling the number of the correct response
,
Barium combines by (1) gaining two electrons, (2) losing two
electrons, (3) sharing two electrons, (4) sharing 3 electrons'
2.
Which of the following is the correct electron dot diagram for
1
nitrogen?
.
'$ff: 'lFtr' -ry- lN_
(1)
3.
(z)
(3)
(4)
ln water, the bond between hydrogen and oxygen
is
(1) ionic'
(2) polar covalent, (3) nonpolar covalent, (4) nonpolar
noncovalent.
, 4,
.
('
Which of the following occurs during covalent bonding?
('1) Electrons are lost. (2) Electrons are gained' (3)Valence
electrons fall from the excited state to the ground state'
(4) Unpaired electrons form pairs.
5.
Which of the following is an example of a substance with a
nonpolarcovalentnonOf 1t; HCI (2)Cl, (3) HCIO, (4) NaCl
6.
The electronegativity of sulfur
7.
Which of the following elements has the highest electronegativity?
(1) fluorine (2) chlorine (3) barium (4) hydrogen
ifre tormutaior magnesium fluoride is MgFr' The best explanation
for this fact is that when they combine (1) each of two magnesium
atoms lose an electron and a fluorine atom gains two, (2) a
8.
is
(1) 16, (2) 239'(3) 2'6' (4) 32'
magnesium atom loses two electrons and each of two fluorine
atoirs gains one, (3) a magnesium atom shares two electrons with
two fluorine atoms, (4) each of two magnesium atoms share an
electron with a fluorine atom'
9.
When calcium combines, it usually (1) loses two electrons,
(2) gains six electrons, (3) shares two electrons, (4) shares six
electrons,
l0,Whatisthemaximumnumberofatomscarboncancombinewith
at once? (1) 1 (2) 2 (3) 3 (4) 4
@ Evan P.
Silberstein,2002
-1
9-
)
Chemistry Regents
Name
Drawing Lewis Diagtams for Ionic & Covalent Bonds
Chemical
formula
Compound
name
LeWis Dot Iliagram
Type ofBond
Fz
HCI
K,S
Ntrogen
H20
Carbon
dioxide
Barium
chloride
Oxygen
NH3
-20-
at)
d
o
oI)
(.)
k
o
C)
U
>'
k
cs
tr
a
bo
g
rd
rlt
al
BI
Fql
E
(u
H
H
($
z
-21-
C,hs..t?istl{: Form
ws4.4.1A
Pe
BONDING
r 10d
llrrs Proy'erbi'es o/ Metais
Until about 5,000 8.C., people made tools and implements from
stone. Around 5,000 B.C.,lt *u, probably noticed that melted
copper ran from green ore in a pottery kiln' Around that same
time, gold *u, Jirro',rered and used for decorations' Metals
B.c.'
becam-e prizedfor jewelry because of their luster. By 3500
tin
with
together
humankind discovered that melting copper
formed a harder metal, heralding the start of the Bronze Age.
Around 1500 B.C., technology leapt forward once again when the
hotter ovens of that age enabled the extraction of iron, an even
harder and more abundant metal, from its ore' In many ways, we
are still in the Iron Age. Modern civilization depends on alloys
of iron for its bridg"r, ikyt"tupers, and automobiles' The physical
properties of metals thai make them so useful are due to metallic
to"Oing which makes them both strong and flexible'
questions that follow based on your
Read the description of metallic bonding below, and answer the
knowledge of chemistry and metals in particular'
Metallic Bondine
1. Why are metallic bonds both strong and flexible?
Metals have low ionization energies. This means they
hold onto electrons loosely. As a result, in a metal
crystal, the valence electrons move easily and do not
belong to any single atom. Since the atoms in the
crystal do not hold on to their own valence electrons,
thby become like cations in a sea of mobile electrons'
The attraction between the cations and the electrons
holds the metal crYstal together'
2.
Why are metals able to conduct both heat and electricity
well?
Grounj
,--e {rt
^
{-t
,_"o.; ;@,*.
r,:J rr\
.@
,S
tj '';\UJ
('i fr*' u)
!-7
3.
mdal
f-\ \:#'
\E]
Group 2 mttal
^--'8,-.O
.^'F)Qt t'?j,€l*,, ffi
fle',-tu)*,,.,
(D*k;rs fi;J (.0
r_-' (D
" 6|e
€J-gi*
'.^O- fi (4)
light shines on them' Then they
The valence electrons of metals jump easily to a higher energy orbital when
fall emitting the excess energy
as
light. Which property of metals is explained by this?
O Evan P. Silberstein,2002
-22-
Ohemisb'rcl: Eorm Ls4 .4A
Name
BONDING
Date
Mstai
Lle fuo nd,s and,
Period
Intgrlrrolgcvlar Forcgs
.4rn
. Examine bonds that are not chemical bonds
),,bbcs
Metallic bonds
*
Formation
* in metals, electrons are easily lost or transferred
* the electrons in metallic substances are not always associated with any particular atom
* as a result, the particles of a metal are usually positive ions surrounded by mobile electrons to which they are
attracted
Properties
strong bonds result in high melting points
mobile electrons result in luster, flexibility, and good conductivity
Intermolecular attractions - forces of attraction between particles that are not chemically bonded
*
*
*
*
*
Dipole-dipole attraction
*' Dipole - a polar molecule, or
a molecule with an asymmetric, or unequal, distribution of charge causing one end
of the molecule to be positive while the other is negative
* Definition - force of attraction between the positive end of one dipole and the negative end of another
Hydrogen bonding
* Definition - ui int"r*olecular force linking an electropositive hydrogen that is covalently bonded to a small
electronegative element such as oxygen, nitrogen, or fluorine, to another electronegative element of the same or
another molecule
@ Hydrogen
O Oxygen
*
rVr+ +
r"% tr@
q'J
-
MS
+ +\Vr_
int of water
Evidence - uncharacteristically
50
O
o
L
(5
0
o
oE
o
F.,
-50
-100
40 60 80
Atomic Mass
-23-
100
120
140
F
*
-the
These are the forces responsible for low
Three types of interrnolecular
forces-
forces-
1.
ex.
force holding two HCL molecules together in the liquid phase:
H
CI<->t-t Cl
dipole-dipole lorce
*Why does it exist?
of attraction-
t,
- a special type of
2.
dipole-dipole
force.
FOUND BETWEEI''{ any molecules containing
bonded to an elernent with
and
*(
h
e
s
bonded to
)
""*THE BIG ThIREE MOLECULES WITI-I HYDROGEN EONDING:
it
'!
-24'
I
i
Why is hydrogen bonding so strong?
H-O':
H-O:
!
!
H
H
TO EXPI.AIN PHYS|CAL
EXAMPLE OF USING I.IYDROGEN tsONDING 'jj'?'':
'PRO'PE"F}T-|'ES':'
CHART OF BOILING POINT VS. PERIOD
Why are the boiling points of H2O, HF, NH3 so high?
.
Summarv:
1.
What is a dipole-dipole force?
2.
What is special about hydrogen bonding?
3.
What elements must be bonded to hydrogen in a molecule to a!!ow the
molecule to rnake hydrogen bonds to other molecules?
*4- What kind of bonds are found lN a water rnolecule?
*5. What kind of bonds account for water's higher melting point than
most molecular substances?
!^l
'
-25-
i3.
Lasi type of intermolecular force:
Forces-
the F
o
between
*VDWF exist because I
can be created ln nonpolar molecules
other
if the molecules are close to each
ex.NN
P-N N
NN
lnstantaneous dipole
lasts for a split second- then electrons move back
This bonding is so weak that most nonpolar molecules exist as gases,
but .liquids and solids due. exist. ' These have
*How do Van der Waals forces chanEe as molecular size (mass)
inc reases ?
AsM
VdW
the strength of
S
th{ow do VDWF change as molecules are brought closer together?
As distance between molecules
VDWF
(_.
26sU
example questions-
1. Which has the strongest Van der Waals forces?
2. Ne (t)
3. Ar(t)
4. Kr (t)
1. He (t)
2.
p
Which has the highest melting poinU boiling poinV lowest vapor
ressu re ?
2. Ne
3, Ar
. He
3. Which has the lowest melting point?
2.CzHa
3. CgHg
1. CHa
1
4,,' l(r'
4.
'-
"
C+HIO
Summary Questions- All lntermolecular Folces
1.
Why is a dipole/dipole force generalty stronger than van der Waals
Forces?
2.
Which of the following has a higher boiling poiht? Why?
1. HzO
3.
or 2. CH+
How do the following affect the stnength of VDWF?
Molecular size/ mass:
Distance between molecules:
-rr-t+
*)
bI
o
lr
a
q)
cq
X
r{
EI
cJl
bl
trl
hl
3l
6)l
EI
-l
EI
frl
a)l
tsr
EI
-l
rl-)
L
t-
q)
A
FI
a
c)^
<) 'a'
q)
Fi
+J
o
o)
A
-t
L-
xbo
qo
Ei
.=
.: q)
OE
L
>;
a)g
qs
u2a
FTH
it
,=
A
-
()
A
-
-28-
r-o
qalJ
6!
€<
a
theilistrg: Form
WS4
Name
.4 . 3A
Period
Date
BONDING
llhe T.i,ss 6hat futna
Pure substances can be held together by ionic bonds, covalent
bonds, metallic bonds, or intetmolecular forces. Most materials
are mixtures, and are held together by a mixture of these forces.
Figuring out what holds things together takes some serious
analysis. If the substance is pure and you know the formula, you
can figure out the electronegativity difference. If it is 1.7 or
greater, than it is ionic. All ionic substances are crystalline solids.
Diamonds are also crystalline solids, but they are made of pure
carbon. What does that tell you about the electronegativity
dffirence? Electronegativity differences below I.7 arc covalent.
Large crystals such as diamond or sand (SiOr) that have a
network of covalent bonds are called macromolecules or
network sotids. Smaller compounds containing covalent bonds
are called molecules. The molecules of a substance may be
attracted to each other to form solids or liquids by
intermolecular forces. These are often called
molecular compounds. Molecular solids are softer
than covalent solids (network solids) and ionic
solids, because intermolecular forces are weaker than
chemical bonds. The flow chart to the right shows
one way of classifying the types of forces that hold
substances together.
Once you have determined that a material is held
together by intermolecular forces, this can be further
refined. If the substance is polar, it is held together
by dipole-dipole attractions. If the polar substance
contains hydrogen atoms attached to either oxygen,
nitrogen, or fluorine atoms, it forms especially strong
dipole-dipole attractions called a hydrogen bonds.
Hydrogen bonds are responsible for the three
dimensional shapes of many proteins because the
large protein molecule folds in such a way that
hydrogens in one part of the molecule are close to
oxygens or nitrogens in anotherpaft of the molecule.
NnxrPaes
@
-29-
'*;r.dt t'.t; il ffitd'
be ionic bonding, covalerrt
bonding, metallic bonding,
or intermolecular forces. I
't knorv, but I'm stuck.
Sh iny?
Conducts Electricily?
Elem ent on left of
Periodic lable?
Electron eg ativity
differen c e< 1 .7 ?
The Ties that Bind
C.hemisttvl: Form WS4 . 4 . 3A
Paoe
BONDING
L
Below are some familiar materials. Based on the reading and your knowledge of chemistry, state whether
samples of these materials are held together by ionic bontls, covalent bonds,, metsllic bonds, dipole-dipole
attractions, hydrogen bonds, or other intermoleculat forces.
1.
Water [HrO(0)]
2.
Table sugar [CrrHrrOrt(s)]
3.
Table salt [NaCl(s)]
4.
Iron railing [Fe(s)]
5.
Liquid oxygen [Or({)]
6.
Diamond [C(s)]
7.
Salt substitute [KI(s)]
8.
Alcohol [CH3CH2OH(0)] . .. . .
9.
Chlorine [Clr(g)]
10.
Gasoline [C8H18({)]
11.
Gold [Au(s)] . .
.
12. Rust [Feror(s)]
13.
Tarnish [AgrS(s)]
14. Tooth enamel [Car(POo)r(s)] . .
15.
Copperwire [Cu(s)] . . ..
.. ..
O Evan P. Silberstein,2jj2
-3
0-
tharnistrgt: Form
WS4 . 4
Name
.2A
Period
Date
BONDING
I obernaT,e evlar Fcq r g I
c
Complete the observations below and answer the questions that follow.
. Fill a 50 mL beaker most of the way with water.
. Continue adding water one drop at a time
. note how high the water can go without spilling.
1.
Describe what happened when you kept adding water to an
already full beaker? Draw a picture of how it looked in the
space to the right. Why does this happen?
-
2.
The graph to the right shows the boiling point of compounds
of hydrogen and members of the oxygen
family.
a. What is the electronegativity difference in
each
I
compound?
BoilinS Foints of Related {]ilmpounds
J
100
50
il,
ffi
rt-
tt
d:
b.
How can the differences in the boiling points be
E
ilJ
F
-5U
explained?
E[ ED 10tl
Ftumir
3.
What holds many solids and liquids together?
O Evan P. Silberstein,2002
-31 -
l+1ass
1:n
14n
thernistrf
Metattic Bonds and Intermolecular Forces
: Form Ls4 . 4A
Page
BONDTNG
2
Answer the questions below by circling the number of the correct response
1.
2.
Which substance will conduct electricity in both
and the liquid phase?
(1)Ascl
(2|H,
(3)Ag
(4)HCr
9,
(a)Hcl(s)
10.
Which molecule is a dipole?
(1)H,
(2) N,
(3)CH4
( 4) HCr
The strongest hydrogen bonds are formed between molecules of
(3)H,o
(1) H,Te
(4) H,S
(2) H,Se
5.
What type of bonds are present in a strip of magnesium ribbon?
3 metallic
1
4 van der Waals
2 ionic
7.
(3)Hr
(4)H,o
(4)co,
Mobile electrons are a distinguishing characteristic ol
3 a metallic bond
1 an ionic bond
4 a covalent bond
2 an electrovalent
(2)H,o
13.
Which substance, in the solid state, is the best conductor of
electricity?
(3) NaCl
(1)As
(2)t,
(3)sio,
(2)Au
12. Which substance is made up of molecules that are dipoles?
(3)CH4
(1)N,
Hydrogen bonds are most likely to exist between molecules of
(2) CH4
(1)Ar
11. Which kinds of bonds are found in a sample of HrO(s)?
t hydrogen bonds, only
2 covalent bonds, only
3 both ionic and hydrogen bonds
4 both covalent and hydrogen bonds
covalent
(1)H,
Which substance exists as a metallic crystals
bond
4.
6.
Which is the predominate type of attraction between molecules ol
HF in the liquid state?
3 ionic bonding
t hydrogen
2 eiectrovalent bonding 4 covalent bonding
bonding
Hydrogen bonds are strongest between molecules of
(3) HF(g)
(1) HB(g)
(2)Hl(g)
3.
8.
the solid phase
Which element consists of positive ions immersed in a "sea" of
mobile electrons.?
3 calcium
1 sulfur
4 chlorine
2 nitrogen
(4)co,
@ Evan P.
Silberstein,2002
-32-
(4)co,
thsmistv9:
Name
Form WS4.3.5A
Period
Date
RONDING
Ala*z;ri;g' Futbing ib aLL ftogatlter
Following the flow
Below is a flow char-t showing the steps to follow when naming a compound from the formula'
and when to look
chart will enable you to deteimine when to use the stock system, when to use a set of prefixes,
up the names of polyatomic ions in Table EEinan, comForlrrd?'
(Only I elenrente)
h,leial present?
Fr'lTalnmir ton
ur i':ns ptesent?
I
q r.,Lc
Daes metal fntm
nror* than onr cation?
{l"4nre than orre oilidatiorr statej
,DeieriniGilid ihar.qt of 'ihe
catit'ns; Utoc ri ii'min
nun'eial after tht tltrtreni
rreme lni the
tatjt'n.
:
The compounds below are of several different types. Use the flow chart to determine the naming system to
use and name each compound shown below.
9. BrrO
1. FeQrlOr),
2. NqSrO,
3.
...
10. HgSO,
1
P2Os
t.
AlrO3
4.BaBrr.....
12. SCl6
5. Mnr(CrrOt)t
13. IFi
6. CaCl, .. ..
7. G.JH4)rS
14. Cr(COr),
.
,..
15.
KNO" ..
16. AuP
8. CuF
@ Evan P.
Silberstein,2002
-33-
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Date
Regents Chemistry
Bonding Practice
Name
Ms. Tintella
8. Which molecule contains a polar covalent bond?
1. Which formula represents a molecule having a
A)T
A)
B)H
H_C- N_ H
tt
HH
c)HHD)
tl
H-C- C-H
ttt
HH
c)
I
H-C-
l-{
.x
H
H
H
9. Given the formula representing a molecule:
I
H_C-OH
H_C = C_H
H
The molecule is
A)
B)
symmetrical and polar
symmetrical and nonpolar
C) asymmetrical and polar
D) asymmetrical and nonpolar
A) C-N B) H-H C) S-Cl D) Si-O
3. Which formula represents a nonpolar molecule
containing polar covalent bonds?
A) HrO B) CCI+ C) NH: D)
Hz
10. Which electron-dot structure represents a
non-polar molecule?
4. The bonds between hydrogen and oxygen in a
water molecule are classified as
H
H:C:H
H
ii
5. Which type of molecule is CF+?
A) polar, with a symmetrical distribution of
, H:O:
D)
charge
B) polar, with an asymmetrical distribution of
ii
charge
C) nonpolar, with a symmetrical distribution of
1
charge
an asymmetrical distribution
1. Two fluorine atoms are held together by a
covalent bond. Which statement correctly
describes this bond?
of charge
A) It is polar and forms apolar molecule.
B) It is polar and forms a nonpolar molecule.
6. Which compound has molecules that form the
strongest hydrogen bonds?
C) It is nonpolar
D) It is nonpolar
B) HBr C) HF D) HCI
and forms a polar molecule.
and forms a nonpolar
molecule.
7. Which electron-dot diagram represents a molecule
that has a polar covalent bond?
..
A)
' HiCt:
..'it
n\
v):.cligll
B)
A) H ,-cl:
..
C)
,H:N:H
A) polar covalent B) nonpolar covalent
C) ionic
D) metallic
A) HI
H;H
D):N:itrtl
;;ii, ,
I
2. The chemical bond between which two atoms is
most polar?
D) nonpolar, with
B)
XX o.
, II;I:
nonpolar covalent bond?
12. Given a formula for oxygen:
B) ur gbj:l D) r.
[:9j:] -
:o--o:
shared
What is the total .r,rrnb". of
"I"",.on,
between the atoms represented in this formula?
A)1
-35-
B)2
c)8
D)4
Bonding Practice
19. Which characteristic is a property of molecular
13. What is the total number of pairs of electrons
shared in a molecule of Nz?
A) one pair
C)
three
pairs
substances?
A) good heat conductivity
B) good electrical conductivity
B) two pairs
D) four pairs
C) low melting point
14. What is the total number of electrons shared in the
D) high melting point
bonds between the two carbon atoms in a the
20. In the diagram of an ammonium ion to the right,
molecule shown below?
why is bond I considered to be a coordinate
H_C=C_H
covalent bond?
A)6
B)2
c)3
D)8
15. Which compound contains only covalent bonds?
A) NaOH
C) Ca(OH)z
lHltl -J-tHl
B) Ba(oH)z
D) CH:OH
L
16. Which pair of atoms is held together by a
C) NaCl
shared
B) LiCl
D) KCI
a pair of electrons to be
with nitrogen.
nitrogen.
D) Nitrogen
transfers a pair of electrons to
hydrogen.
B) Nacl($
D) CCl4(l)
18. Which is the correct electron-dot formula for a
hydrogen molecule at STP?
A)
l
shared with hydrogen.
C) Hydrogen transfers a pafu of electrons to the
covalent bonds?
HCI(g)
C) NH+Cl(s)
uono
B) Nitrogen provides a pair of electrons to be
17. Which compound contains both ionic and
A)
'H-
A) Hydrogen provides
covalent bond?
A) HCI
I
l-H
I
xx
H' B) H: C) H'H D) H:H
-36-
Date
Bonding Practice
Name
Regents Chemistry
Ms. Tintella
Base your answer to questions L through 3 on the table below.
PhYsical ProPerties of Four Gases
Name of Gas
Molecular Structure
Boiling Point (K) at 1 Atm
Density (g/L) at STP
1.
hydrogen
hydrogen
chloride
hydrogen
bromide
hydrogen
iodide
H_H
H-Cl
H-Br
H-l
20.
188
207
237
0.0899
1.64
,)
5.66
hydrogen in
Explain, in terms of molecular polarity, why hydrogen chloride is more soluble than
water under the same conditions of temperature and pressure.
point than
2. Explain, in terms of intermolecular forces, why hydrogen has a lower boiling
hydrogen bromide.
3. Explain, in terms of electronegativity difference, why the bond in
H-Cl is more polar than the
bond in H-I.
4. Draw a Lewis electron-dot diagram for a molecule of phosphorus trichloride, PCh
Base your answer to questions 5 and 6 on the balanced equation below'
2Na(s) + CIz
-->
2NaCl(s)
5. Draw a Lewis electron-dot diagram for a molecule of chlorine, clz.
6. Explain, in terns of electrons, why the bonding in
Nacl is ionrc.
-37
-
Bonding Practice
7. Base your answer to the following question on the information below.
Each molecule listed below is formed by sharing electrons between atoms when the atoms
within the molecule are bonded together.
Molecule-4: ClzMolecule B: CCI+Molecule C: NII:
Explain why CCl4 is classified as a nonpolar molecule.
8.
Bromine is the only liquid nonmetallic element at room temperature. It is a heavy,
mobile, reddish-brown liquid, volatilizing readily at room temperature to a red
vapor with a strong disagreeable odor, resembling chlorine, and having a very
irritating effect on the eyes and throat; it is readily soluble in water or carbon
disulfide, forming a red solution, is less active than chlorine but more so than
iodine; it unites readily with many elements and has a bleaching action; when
spilled on the skin it produces painful sores. It presents a serious health hazard, and
maximum safety precautions should be taken when handling it.
a
b
Draw the electron-dot diagram of a molecule of bromine, Brz.
Why does bromine have properties resembling chlorine?
9. a) Draw the structural formula for HzO.
b) Is this molecule polar or nonpolar? Explain your answer.
10. The natural gas delivered to consumers in the U. S. is about 95o/omethane (CH+, molecular
weight 16 g/mol) with the remainder being mostly ethane, propane, and carbon dioxide.
Draw the Lewis electron-dot strucfure for
a
molecule of methane.
-38-
Bonding
What will students know and be able to do by the end of this instructional unit?
1.
Define and recognize:
f. Metallic Bond
a. AsYmmetrY
g. Molecule
b. Chemical Bond
h. Nonpolar
c. Covalent Bond
i. Polar
d. Intermolecular Forces of
j.
Polyatomic Ion
Attraction
k. Symmetry
e. Ionic Bond
2. Compare Ionic & molecular compounds
3. Explain properties in terms of their corresponding bond types
4. Interpret and draw lewis dot diagrams
5. Assess polarity of a bond by using their elements electronegativity values
6. Use the type of element to predict the polarity of the bond
l. Differentiate between intermolecular forces
g. Identify and differentiate polar and nonpolar molecules
g. Apply "like-dissolves-1ike" to real world applications
and behavior
f O. fde*ify the effects of intermolecular forces on physical properties
rate and phase
evaporation
pressure,
1 1. In terms of intermolecular forces, explain vapor
changes
forces, and
12. Interpret VP curves in terrns of boiling points, evaporation, intermolecular
relative vapor Pressure
point and
13. Explain colligative properties of solutes on water's boiling point, freezing
vapor pressure
Key Subject ComPetencies
o
o
c
o
.
o
o
c
o
o
o
Explain energy changes associated with forming chemical bonds.
Describe the octet rule and how it relates to chemical bonding.
Describe what a noble gas configuration is and determine the n.g.c. for different
elements.
Explain how ionic bonds form and the properties caused by them (ionic substances)'
Explain how covalent bonds form and the properties caused by them (network-covalent,
mo I ecular-covalent substances).
a compound's bond
Use the electronegativity difference between 2 eiements to determine
type.
Explain how metallic bonds form and the properties caused by them.
ljse element types (metal + nonmetal; only nonmetals; only metals) to determine what
bond type is present in a substance.
Describe what polyatomic ions are and how to draw them in compounds'
Draw bond types (ionic or covalent) using Lewis Structures'
to conduct electricity'
Exptrain now a substance (metallic or aqueous/melted ionic) is able
able to conduct
NoT
Explain why a substance isolid ionic oimolecular or network) is
electricitY.
-39-
Bonding
.
r
o
o
.
Explain and draw the difference between a single-covalent, double-covalent, and a triplecovalent bond.
Determine and describe what it means for a bond to be a polar bond or a nonpolar bond,
using charge symmetry.
Determine and describe what it means for a molecule to be polar molecule or a nonpolar
molecule, using charge symmetrY.
Describe what an intermolecular force of attraction is and how they affect properties such
as solubility, melting point temperature, and boiling point tempetature.
Prioriti ze the types of intermolecular forces of attraction based on their strengths of
attraction between molecules
Vocabulary
o Anion
o
o
r
o
o
o
.
.
.
.
o
o
o
o
o
.
o
.
.
r
o
Ion
Octet Rule
AsymmetricalMolecule
Ionic Bond
Polar Covalent Bond
Cation
Ion-Molecule
Symmetrical Molecule
Chemical Bond
Lewis Dot Diagram
Triple Covalent Bond
Covalent Bond
Metallic Bond
Van der Waal's Forces
CrystalLatticeMolecule
Dipc,le-Dipole
Multiple Covalent Bond
Hydrogen Bond
Nonpolar Covalent Bond
IntermolecularForces
Octet
-40-
Class
$:-"
Lab #
Covalent Cornpoundsaiiraciion
iecrronega:ivi-'y is a scale usec io deterqine an aiorn's
in ihe bonding process' Differences in
for an
"'iu.aronare usec
preCicr whether ihe bonci is pure
elec,-ionegaiiviries
"o
ccvaient.lolar covafent, or ionic' Molecules ln which the
pure
elecrronegariviq/ direrence is zero are consicjered to be
difference
ccvalenr. Tnose molecules -,.har exhibit an elecironegativiiy
covalent'
polar
as
of more ihan zero but less than 1.7 are classified
lonic crystais exisi in those sysiems ihat have an elecironegativiiy
diirerence of more than 1.7'
The str.uciures used to snow the bonding in covaient molecules
a
are calleC Lewis siruciures. When bonding' atoms iend io achieve
can
atorns
noble gas configuration- By sharing e{ecirons, individual
of
ccmplete the outer.n*tgy level' ln i covalent bond' an ociet
elecircns is formed around each aiom (except hydrogen.)
To study covalent molecules, chemists tind the use of models
aioms'
heloful. Coiored wooden or plasiic bails are used to represent
of
These balls have holes drilled in them according'Lo ihe number
thai
angles
at
bored
covaienl bonds they will form. The holes are
acproximaie ihe accepted bond angles'
*to represeni bonds' Singte bonds are
Siicks and springs are usecj
with two
shown with sticks, tirf,ile aouOle and triple boncjs are shown
aioms
sorings anci three springsl respeciiveiy. While the sizes of the
represent
io
u.u nlt propofrionateiy correcr, the modeis are usefui
the arrangement oi thl atoms acccrding to iheir bond angles'
,i,
g\
,
Problem
How can tr,re determine rhe
type of bonds in a compound and draw and
cons-iruct models of molec
-.r
ies
?
Objectives
. Construct models to show
tne shape: of some
covalent ccmpounds. Draw a Lewis representerion of the nructure of
.
Materials
wooden or plastic molecular model set
(bail and stick)
p
el
liers
ectrone gativitY ta b les
some molecuiesCompare models anci
Lewis strucures of
molecules.
Safety Precautions
'i+l IEI=
li't
E:l
v\
Aiways wear sa-fety goggies ancj a iab apron'
l
-41
-:.cr=:3T,,!lanuai
-
'a'-=^r.=.
C:rer':rs:ry: ivia;:' zllC -' cri9=
Pre-Lab
1. Defr.ne ccvaieni bond.
Z. Give the eieciron coniguranon cf cxvgen'
hycirogen- nirogen. anci carbonof o;<vgen'
F{ow miny covaienr bonds wili each
3.
hydrogen. nirogen, anci
4.
crbon ionr'?
Your work' iis4. .A:ter your ieacher has clecked
asseinbie rie moiei'
, ,
tbe ccnoounis
5. F.:peai st3cs l-- lfor :ace of
iisted i:: Daia Table 3'
Table
1
are
Describe how eiec'*orregattviw iiftarences
covaieni'
pure
used to predicl whether a bonci is
polar covaienl or ionic'.
laboratory utritlT'lo"t-u
or
hypothesis about how to snow sn3iinq
elecrons in a covalent bond in an iliustration
bond is
and in a rnociel and bow the type of
on page ?1'
derermined- Record your hypothesis
5. Read the enti-re
pure ccvaient
zerc I
but less ihan 1.7 |
Greater ihan
I
-
Part A
1. Look at your ball-and-stick model sers' ldeniify
single
the diffeient pieces rhat represenl atoms'
bonds
uiple
bonds, double bonds, and
2. Select one of every difrerent color ofball' Each
rePre'
hole that has been boreci into the spirere
the number
sents a single chemical bond' Count
balis'
colored
difrerent
of holes present in rhe
1'
Data'Table
Recbrd y'our observations in
ElectronegativitY
difference
polar covalent
1.0
in the ccmciifference between the two elements
Part
colar covalent
l
potrt .9"15n1
|
I
Polar covaieni
potut covaleni
e
potur. covalent
I
2-
C
1. Consti-ucr
z-
I
I
!-por"'. coualent
polar covaleni
2'
Pounds in Data Table
the
Use the rables on the right rc deterinine
character and bond type of
Percentage of ionic
answers on
Lach of tbe comoounds' Record your
Dara Table
Type of bond
I put. covalent
Part B
i
1. Use an eiecuonegalivily table (see page i69.in
your textbook) ro derermine rhe electronegauvlr-Y-
2.
colar covalent
G;'eater than
Procedure
-
io*pur"
#
mociel for H"
-*le eiecuone gativiry dif'erence ior'"he
h'
of
aloms in ihe rnoiecule and irienriry ''he rype
3'
Table
Dara
bond. Record your answer on
in ihe
3. Draw the L:wis su'uciure for the nolecuie
srace proviiei on Data Tabie 3'
Crer:',is::-v: Nia-ei anc Clan-ce '
uabora-uory Manuai
-42-
F-
)
CleanuP and DisPosal
Hypothesis
:
)..
I
1. Be sure aii sacks anC spnngs iiave be:n renoveC
f;crn 'J:e soheres2. Neariy reassembie the mcdei H.t.
i-i
,
I
Data and ObserYations
Ball
color
I
ldentity of element
Number of holes
Keo
oxygen
Orange
bromine
Yellow
hydrogen
ch
Green
n
Elue
\r')
Formula
e
iirogen
iodine
Purp le
Black
-l
lorin
I
ca
I
Electronegativity diff eren ce
rbon
Percent ionic character
i
fype of bond
z
a
CaCI,
MgS
o
I
I
,*,')
i-zcateaarl iVlanuai
-43-
C,:enis:,-r: ivlacea :nc C':ang*
'
Molecule
ElectronegativitY
difference
Type of bond
Lewis formula
AnalYze and Conclude
l.observingandlnferring!'9$iwacerandc:rbcndioxidealeirialorjicmolqcules.
Explain
c-ire
meaning ai rr;'arcmic'
2.CollectingandlnterpretingData.CcmparetheapoearanceofiheLewisstr.rcrurefor
t'I""-t"*tlolil " bali and siick model of the compound'
3. Predicting
ibr CBru
Predicr the shrpe and Lewis strucrure
i
o
a formula wirhoul
4. Drawing a conctusion E.rclin Yn,
,,*.*r--..nnot be used lo pr:cict bond rype'
elecT onegarivitir date or a Lervis
y"-"::::1]t'--
.lr:
su-ucrures- Do
the errors?
anY
you ccnsrucieC,wiih
Cornpare the bail and stick modeis
\!'nat cculi 'oe some c3uses
iheni ,jifrer in ihe number of bonds?
icr
oi
I
I
€'
2.
nt
1. Expiain 'whY water is a Ucuic roorll
is a gs'
iicx:ce
,-*r.rar::r= and cs'i;cn
t-"ifo:. 'rgre:retij-r1
Sociilm :i-rcnce
l"C'
incri -r-ails- neirs ac S0
(|iaCi)' colnmco tebie salt' nlix.et 3Ll0'7"C'
Nachthaiene
iC,o;{.)'
e
nei-'jlg pcinrs i::dicrre 'lbe-ui ine
boncino :ai:e= oi- e:c:: :cmccund?
Wtu, *o
;nc Ci:ar:-ce '
-44-
rhese
L;ccr:icry fuia.u;j
1*A
Date
,J.lame
Lab #
Mo
F;
; --'r Three-D!{ensional
Molecules
\
-
of Covalent
Text reference: Cha;,
Pre-Lab Discussion
pai'r of elecw'hen fwo atoms share a
A sin.gie couslsrLt bor)_.tsformed
H the two
J" "t""oo* of the pair'
are
Fons. Each "** n'Jii*'' ""t "t
nnnpalar ca1)darlt' U the aloms
to be
etoms are alike' the bond is said
the bond
force on tlre electrons' and
gretl''atrtctite
Tttis
unlilie, one exerts a
pair of elecirons can be shared'
one
is polnr copal'en't'U"" th*
bond'
triple
or
resuits in a double
a rnnlecilz.
u1c15]ent' bonds is csled
A gsoup of atoms ntii i!"tn"r
nonpolar' t}re
polar or nonpolar. If bonds are
h{olecr:jes can be eithqr
be nonpolar
are polar, molecules can still
-*rroughout
molecule is nonpolarlu-uona.
the molecule is syrnmetrical' A
if the charge aitctiU'irion on'its:h11"'
rhat is' the posirions in space
molecule's **"ot"llp"nas
lineat'
Some possible shapes are
of the atoms malring;;*t molecule'
tetrahedral'
ang:lar (bent), pf;d"l' and
on-paper as being fwodirnensional
molecules
*. ,.tp'"'"nt
'
molecu'
o. AJthough
three-<iimensional. By bui-lding
for convenien.", *"r'rr""'""*r:rv
polaritV
and
shapes,
bond"ing.
.Iar
models,
oi uu"n the
--l
chemists:;;; ""i.rsu'd
most compiex molecu'les'
the
FT
PurPose
Buildtlrreedimensiona]mqdelsofsomesimp]ecovalentmolecu]es.Pre.
dicttheirshapesarrdpolaritresfromt.no''t*ag.ofbondsarrdmolecule
polariry rules.
EquiPrnent
molecr:liu model building set
t
safety E et
safet-v goggles
be follou'ed' Als'a-vs wear
Ail general lab safet-'r rules should
working in the lab'
and a lab apron or cott whtn
,
Y
t
+
4
-+t
'=-
Procedure
'
sel Study tlre color code
1. Obi;i! a molecular model buiiding
aLoms'
idenffiing the different kinds of
har'e one hoie @onding
.9. observe-t}rat the folJo*-ing a.t,oms
bi:omine' and iodine' The
stre): h.vdrogen" fluorin"' "hll'int'
a:id sulfur.' A nitrogen atom
atoms *'ith rg,.o ho]es are oxllgen
holes'
hrc
'ittt:noi"='
and a carbon atom has fou'--'-:
-::
-'. ::::;--:'i-45-
'
-re'
q12-116
8.
t'
I
H2
HF
Hzo
QHe
cHzclz
o2
Nz
Hss
ctl
cl,
NH3
1r
t'
Constr'r:ct models of the foUowing molecules:
I
4.
cH3oH
Hzoz
c;f
(
'{
COz
Becord yor:r obsenations betow.
Observations and Data
Struchlral
Name
Formula
hydrogen
Shape
polariry
H-H
H2
water
Molecule
represen_tation
o
Hzo
H
H
.
methane
cllr
cNorine
Clz
I
H_C-H
,l
H
ct-{t
I
,8,.,
W
H_N_H
arnmonla
NHa
I
H
rr
hydrogen fluoride
H-F
?.
etJryne
QHz
l..l-i:a--lJ
t
H
.
dichloromet}ane
cH?ct2
.-
-L
H-€--ct
I
o
nitrogen
N2
N=N
H
methanol
-
-' --s--^-:T '
I
CH3OH
:
H-C-OH
I
H
H
_..
hydrogen peroxide ':;
- ' HzOz
=
/
o-o
tsL-a-
o)rygen
Oo
ti n-n
{
78
Models of covalent Molecules
Thr*-Di'F.*ional
I
{coniinued)
il
Conclusions and Ques'rions
1. lltrich
all bonds were nonpolar?
molecules were nonpolar because
.jj
b€cause
pobr covalentbonds but were nonpolar
ffi
of sYmmetrY?
3.
*r
4.
StLich mo shapes appeared
Name f,wo tJrpes
.:' covaient bonds'
produce polar molecules?
"'o
of substances that do not
contain rnolecules with
|_