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CHAPTER 2
CHAPTER 2
CHAPTER 2
CHAPTER 2
INTERATOMIC FORCES
INTERATOMIC FORCES
INTERATOMIC FORCES
INTERATOMIC FORCES
What kind of force holds the
What kind of force holds the
atoms together in a solid?
Inte
rato
mic
Bin
din
g
�A
llo
fth
em
echa
nis
ms
wh
ich
ca
use
bo
nd
ing
be
twe
en
the
ato
ms
de
rive
fro
me
lectr
osta
tic
inte
ractio
nb
etw
ee
nn
ucle
ia
nd
ele
ctr
on
s.
�T
he
diffe
ring
str
eng
ths
an
dd
iffe
rin
gty
pes
of
bo
nd
are
de
term
ine
db
yth
ep
art
icu
lar
ele
ctr
on
icstr
uctu
res
ofth
ea
tom
sin
vo
lve
d.
�T
he
exis
tence
of
asta
ble
bo
nd
ing
arr
an
ge
me
nt
imp
lies
tha
tth
esp
atia
lco
nfig
ura
tio
nof
po
sitiv
eio
ncore
sa
nd
ou
ter
ele
ctr
ons
has
less
tota
le
nerg
yth
an
an
yo
ther
con
fig
ura
tion
(in
clu
din
gin
fin
ite
se
para
tio
no
fth
ere
sp
ective
ato
ms).
�T
he
en
erg
yd
eficie
nce
of
the
co
nfigu
ratio
ncom
pare
dw
ith
iso
late
da
tom
sis
kn
ow
nas
coh
esiv
ee
nerg
y,
an
dra
ng
es
inva
lue
from
0.1
eV
/ato
mfo
rso
lids
wh
ich
ca
nm
uste
ro
nly
the
we
ak
va
nd
er
Waa
lsto
7e
v/a
tom
or
more
insom
eco
va
len
tand
ion
iccom
po
un
ds
an
dso
me
me
tals
.
Energies of Interactions
Energies of Interactions
Energies of Interactions
Energies of Interactions
Between Atoms
Between Atoms
Between Atoms
Between Atoms
�T
he
en
erg
yo
fth
ecry
sta
lis
low
er
tha
nth
at
of
the
fre
ea
tom
sb
ya
na
mo
un
te
qu
al
toth
ee
ne
rgy
req
uir
ed
top
ull
the
cry
sta
la
pa
rtin
toa
se
to
ffr
ee
ato
ms.
Th
isis
ca
lled
the
bin
din
g(c
oh
esiv
e)
en
erg
yo
fth
ecry
sta
l.
�N
aC
l is
mo
re s
tab
le th
an
a c
olle
ctio
n o
f fr
ee
Na
an
d C
l.�
Na
Cl is
mo
re s
tab
le th
an
a c
olle
ctio
n o
f fr
ee
Na
an
d C
l.
�G
e c
rysta
l is
mo
re s
tab
le th
an
a c
olle
ctio
n o
f fr
ee
Ge
.
Cl
Na
NaCl
�T
his
typ
ica
l cu
rve
ha
s a
m
inim
um
at
eq
uili
bri
um
dis
tan
ce
R0
�R >
R0 ;
�th
e p
ote
ntia
l in
cre
ase
s
gra
du
ally
, a
pp
roa
ch
ing
0
as R
�∞
�th
e fo
rce
is a
ttra
ctive
V(R
) 0R
Repuls
ive
�th
e fo
rce
is a
ttra
ctive
�R <
R0;
�th
e p
ote
ntia
l in
cre
ase
s
ve
ry r
ap
idly
, a
pp
roa
ch
ing
∞ a
t sm
all
se
pa
ratio
n.
�th
e fo
rce
is r
ep
uls
ive
R
rR
0R
0
Att
ractive
�F
orc
ebetw
een
the
ato
ms
isth
enegative
of
the
slo
pe
of
this
cu
rve.
Atequlib
rium
,re
puls
ive
forc
ebecom
es
equals
toth
eatt
ractive
part
.
Th
e p
ote
ntia
l e
ne
rgy o
f e
ith
er
ato
m w
ill b
e g
ive
n b
y:
or
sim
ply
:
V=decreaseinpotentialenergy+increaseinpotentialenergy
(duetoattraction)
(duetorepulsion)
()
mn
ab
Vr
rr
−=
+
V(r
):th
en
et
po
ten
tia
le
ne
rgy
of
inte
ractio
na
sfu
nctio
no
fr
V(r
):th
en
et
po
ten
tia
le
ne
rgy
of
inte
ractio
na
sfu
nctio
no
fr
r:
the
dis
tan
ce
be
twe
en
ato
ms,
ion
s,
or
mo
lecu
les
a,b
:p
rop
ort
ion
alit
yco
nsta
nt
of
att
ractio
na
nd
rep
uls
ion
,
resp
ective
ly
m,
n:
co
nsta
nt
ch
ara
cte
ristics
of
ea
ch
typ
eo
fb
on
da
nd
typ
e
ofstr
uctu
re
Typ
es o
f B
on
din
g M
ech
an
ism
s
Itis
conventionalto
cla
ssify
the
bonds
betw
een
ato
ms
into
diffe
rent
types
as
�Io
nic
,�
Covale
nt,
Meta
llic
,�
Meta
llic
,�
Van
der
Waals
,�
Hydro
gen.
All
bondin
gis
aconsequence
of
the
ele
ctr
osta
tic
inte
raction
betw
een
nucle
iand
ele
ctr
ons
obeyin
gSchrö
din
ger’s
equation.
1 1 1 1 1 1 1 1 - ---- ---IONIC BONDING
IONIC BONDING
IONIC BONDING
IONIC BONDING
IONIC BONDING
IONIC BONDING
IONIC BONDING
IONIC BONDING
�Io
nic
bo
nd
ing
isth
ee
lectr
osta
tic
forc
eo
fa
ttra
ctio
n
be
twe
en
po
sitiv
ely
an
dn
eg
ative
lych
arg
ed
ion
s
(be
twe
en
no
n-m
eta
lsa
nd
me
tals
).
�T
he
se
ion
sh
ave
be
en
pro
du
ce
da
sa
resu
lto
fa
tra
nsfe
r�
Th
ese
ion
sh
ave
be
en
pro
du
ce
da
sa
resu
lto
fa
tra
nsfe
r
of
ele
ctr
on
sb
etw
ee
ntw
oa
tom
sw
ith
ala
rge
diffe
ren
ce
ine
lectr
on
eg
ativitie
s.
�A
llio
nic
co
mp
ou
nd
sa
recry
sta
llin
eso
lids
at
roo
m
tem
pe
ratu
re.
�N
aC
lis
aty
pic
ale
xa
mp
leo
fio
nic
bo
nd
ing
.
�T
he
me
talli
ce
lem
en
tsh
ave
on
lyu
pto
the
va
len
ce
ele
ctr
on
sin
the
iro
ute
rsh
ell
will
lose
the
ire
lectr
on
sa
nd
be
co
me
po
sitiv
eio
ns,
wh
ere
as
ele
ctr
on
eg
ative
ele
me
nts
ten
dto
acq
uir
ea
dd
itio
na
le
lectr
on
sto
co
mp
lete
the
iro
cte
da
nd
be
co
me
ne
ga
tive
ion
s,
or
an
ion
s.
Na
Cl
�N
otice
that
when
sodiu
mlo
ses
its
one
vale
nce
ele
ctr
on
itgets
sm
alle
rin
siz
e,
while
chlo
rine
gro
ws
larg
er
when
itgain
san
additio
nal
vala
nce
ele
ctr
on.
Aft
er
the
reaction
takes
pla
ce,
the
charg
ed
Na+
and
Cl-
ions
are
held
togeth
er
by
ele
ctr
osta
tic
forc
es,th
us
form
ing
an
ionic
bond.
Na
Cl
�W
he
nth
eN
a+
an
dC
l-io
ns
ap
pro
ach
ea
ch
oth
er
clo
se
lye
nou
gh
so
tha
tth
eo
rbits
of
the
ele
ctr
on
inth
e
ion
sb
eg
inth
eo
ve
rla
pe
ach
oth
er,
the
nth
ee
lectr
on
be
gin
sto
rep
el
ea
ch
oth
er
by
vir
tue
of
the
rep
uls
ive
ele
ctr
osta
tic
co
ulo
mb
forc
e.
Of
co
urs
eth
eclo
se
r
tog
eth
er
the
ion
sa
re,
the
gra
ter
the
rep
uls
ive
forc
e.
�P
au
lie
xclu
sio
np
rin
cip
leh
as
an
imp
ort
an
tro
lein
rep
uls
ive
forc
e.
To
pre
ve
nt
avio
latio
no
fth
ee
xclu
sio
n
pri
ncip
le,
the
po
ten
tia
le
ne
rgy
of
the
syste
min
cre
ase
s
ve
ryra
pid
ly.
Solid
ion
icco
mpoun
ds
do
not
conduct
ele
ctr
icity
wh
en
apote
ntial
isapplie
db
ecause
there
are
no
mobile
charg
ed
part
icle
s.
No
free
ele
ctr
ons
causes
the
ions
tobe
firm
ly
Ele
ctr
ical
conductivity
The
meltin
gan
dboili
ng
po
ints
of
ionic
com
pound
s
are
hig
hbecause
ala
rge
am
ount
of
therm
al
energ
yis
requir
ed
tosepara
teth
eio
ns
whic
hare
bound
by
str
ong
ele
ctr
icalfo
rces.
Meltin
g p
oin
t
and b
oili
ng p
oin
t
Explanation
Property
Most
ionic
com
poun
ds
are
britt
le;
acry
sta
lw
ill
shatt
er
ifw
etr
yto
dis
tort
it.
This
ha
ppe
ns
because
dis
tort
ion
ca
use
ions
of
like
charg
es
tocom
eclo
se
togeth
er
then
sharp
lyre
pel.
Britt
leness
Most
ionic
co
mpoun
ds
are
hard
;th
esurf
aces
of
their
cry
sta
lsare
not
easily
scra
tches.
This
is
because
the
ions
are
boun
dstr
ongly
toth
ela
ttic
e
and
are
n't
easily
dis
pla
ced.
Hard
ness
No
free
ele
ctr
ons
causes
the
ions
tobe
firm
ly
bound
and
cannot
carr
ycharg
eby
movin
g.
2 2 2 2 2 2 2 2 - ---- ---COVALENT BONDING
COVALENT BONDING
COVALENT BONDING
COVALENT BONDING
COVALENT BONDING
COVALENT BONDING
COVALENT BONDING
COVALENT BONDING
�C
ova
len
tb
on
din
gta
ke
sp
lace
be
twe
en
ato
ms
with
sm
all
diffe
ren
ce
sin
ele
ctr
on
eg
ativity
wh
ich
are
clo
se
toe
ach
oth
er
inp
eri
od
icta
ble
(betweennon-metalsandnon-
metals
).
�T
he
co
va
len
tb
on
din
gis
form
ed
by
sh
ari
ng
of
ou
ter
sh
ell
ele
ctr
on
s(i
.e.,
sa
nd
pe
lectr
on
s)
be
twe
en
ato
ms
rath
er
tha
nb
ye
lectr
on
tra
nsfe
r.th
an
by
ele
ctr
on
tra
nsfe
r.
�T
his
bo
nd
ing
ca
nb
ea
tta
ine
dif
the
two
ato
ms
ea
ch
sh
are
on
eo
fth
eo
the
r’s
ele
ctr
on
s.
�S
oth
en
ob
leg
as
ele
ctr
on
co
nfig
ura
tio
nca
nb
ea
tta
ine
d.
�E
ach
ele
ctr
on
ina
sh
are
dp
air
isa
ttra
cte
dto
bo
thn
ucle
i
invo
lve
din
the
bo
nd
.T
he
ap
pro
ach
,e
lectr
on
ove
rla
p,
an
d
att
ractio
nca
nb
evis
ua
lize
da
ssh
ow
nin
the
follo
win
g
fig
ure
rep
rese
ntin
gth
en
ucle
ia
nd
ele
ctr
on
sin
ah
yd
rog
en
mo
lecu
le.
e
e
Poor
cond
ucto
rsbecause
ele
ctr
ons
are
held
either
on
the
ato
ms
or
within
co
vale
nt
bonds.
The
y
cannot
move
thro
ugh
the
latt
ice.
Ele
ctr
ical
conductivity
Very
hig
hm
eltin
gpoin
tsbe
cause
each
ato
mis
boun
db
ystr
ong
covale
nt
bonds.
Man
ycovale
nt
bonds
must
be
bro
ken
ifth
esolid
isto
be
melted
and
ala
rge
am
ount
of
therm
al
energ
yis
requir
ed
for
this
.
Meltin
g p
oin
t
and b
oili
ng p
oin
t
Explanation
Property
Covale
nt
netw
ork
substa
nces
are
bri
ttle
.If
suffic
ient
forc
eis
applie
dto
acry
sta
l,covale
nt
bo
nd
are
bro
ken
as
the
latt
ice
isdis
tort
ed.
Shatt
ering
occurs
rath
er
than
defo
rmation
of
ashape.
Britt
leness
They a
re h
ard
because t
he a
tom
s a
re s
trongly
bound in t
he latt
ice,
and a
re n
ot
easily
dis
pla
ced.
Hard
ness
cannot
move
thro
ugh
the
latt
ice.
Comparison of Ionic and
Comparison of Ionic and
Covalent Bonding
Covalent Bonding
3 3 3 3 3 3 3 3 - ---- ---METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
�M
eta
llic
bo
nd
ing
isth
ety
pe
of
bo
nd
ing
fou
nd
inm
eta
le
lem
en
ts.
Th
isis
the
ele
ctr
osta
tic
forc
eo
fa
ttra
ctio
nb
etw
ee
np
ositiv
ely
ch
arg
ed
ion
sb
etw
ee
np
ositiv
ely
ch
arg
ed
ion
sa
nd
de
loca
lize
do
ute
re
lectr
on
s.
�T
he
me
talli
cb
on
dis
we
ake
rth
an
the
ion
ica
nd
the
co
va
len
tb
on
ds.
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
METALLIC BONDING
�M
eta
llic
str
uctu
res
are
typic
ally
rath
er
em
pty
(havin
gla
rge
inte
rnucle
ar
spacin
gs)
and
pre
fer
latt
ice
arr
angem
ents
inw
hic
heach
ato
mhas
many
neare
st
neig
hbors
.
�The
weakness
of
the
indiv
idualbondin
gactions
ina
meta
lis
due
toth
eenla
rgem
ent
of
the
inte
rnucle
ar
spacin
g.
�V
ala
nce
ele
ctr
on
sa
rere
lative
lyb
ou
nd
toth
en
ucle
us
an
d
the
refo
reth
ey
mo
ve
fre
ely
thro
ug
hth
em
eta
la
nd
the
ya
re
sp
rea
do
ut
am
on
gth
ea
tom
sin
the
form
of
alo
w-d
en
sity
ele
ctr
on
clo
ud
.
�A
me
talli
cb
on
dre
su
ltfr
om
the
sh
ari
ng
of
ava
ria
ble
nu
mb
er
of
++
+
�
sh
ari
ng
of
ava
ria
ble
nu
mb
er
of
ele
ctr
on
sb
ya
va
ria
ble
nu
mb
er
of
ato
ms.
Am
eta
lm
ay
be
de
scri
be
d
as
aclo
ud
of
fre
ee
lectr
on
s.
�T
he
refo
re,
me
tals
ha
ve
hig
h
ele
ctr
ica
la
nd
the
rma
lco
nd
uctivity.
++ +
++ +
++ +
�A
llva
len
ce
ele
ctr
on
sin
am
eta
lco
mb
ine
tofo
rma
“se
a”
of
ele
ctr
on
sth
at
mo
ve
fre
ely
be
twe
en
the
ato
mco
res.
Th
e
mo
ree
lectr
on
s,
the
str
on
ge
rth
ea
ttra
ctio
n.
Th
ism
ea
ns
the
me
ltin
ga
nd
bo
ilin
gp
oin
tsa
reh
igh
er,
an
dth
em
eta
lis
str
on
ge
ra
nd
ha
rde
r.
�T
he
po
sitiv
ely
ch
arg
ed
co
res
are
he
ldto
ge
the
rb
yth
ese
ne
ga
tive
lych
arg
ed
ele
ctr
on
s.
�T
he
fre
ee
lectr
on
sa
ct
as
the
bo
nd
(or
as
a“g
lue
”)b
etw
ee
n�
Th
efr
ee
ele
ctr
on
sa
ct
as
the
bo
nd
(or
as
a“g
lue
”)b
etw
ee
n
the
po
sitiv
ely
ch
arg
ed
ion
s.
�T
his
typ
eo
fb
on
din
gis
no
nd
irectio
na
la
nd
isra
the
r
inse
nsitiv
eto
str
uctu
re.
�A
sa
resu
ltw
eh
ave
ah
igh
du
ctilit
yo
fm
eta
ls-
the
“bo
nd
s”
do
no
t“b
rea
k”
wh
en
ato
ms
are
rea
rra
ng
ed
–m
eta
lsca
n
exp
eri
en
ce
asig
nific
an
td
eg
ree
of
pla
stic
de
form
atio
n.
4 4 4 4 4 4 4 4 - ---- ---VAN DER WAALS BONDING
VAN DER WAALS BONDING
VAN DER WAALS BONDING
VAN DER WAALS BONDING
VAN DER WAALS BONDING
VAN DER WAALS BONDING
VAN DER WAALS BONDING
VAN DER WAALS BONDING
�It
isa
we
ak
bo
nd
,w
ith
aty
pic
alstr
en
gth
of
0.2
eV
/ato
m.
�It
occu
rsb
etw
ee
nn
eu
tra
la
tom
sa
nd
mo
lecu
les.
�T
he
exp
lan
atio
no
fth
ese
we
ak
forc
es
of
att
ractio
nis
tha
tth
ere
are
na
tura
lflu
ctu
atio
nin
the
ele
ctr
on
de
nsity
of
all
mo
lecu
les
an
dth
ese
ca
use
sm
all
tem
po
rary
dip
ole
sm
ole
cu
les
an
dth
ese
ca
use
sm
all
tem
po
rary
dip
ole
sw
ith
inth
em
ole
cu
les.
Itis
the
se
tem
po
rary
dip
ole
sth
at
att
ract
on
em
ole
cu
leto
an
oth
er.
Th
ey
are
ca
lled
va
nd
er
Wa
als
'fo
rce
s.
�T
he
big
ge
ra
mo
lecu
leis
,th
ee
asie
rit
isto
po
lari
se
(to
form
ad
ipo
le),
an
dso
the
va
nd
er
Wa
al's
forc
es
ge
tstr
on
ge
r,so
big
ge
rm
ole
cu
les
exis
ta
sliq
uid
so
rso
lids
rath
er
tha
ng
ase
s.
�T
he
shape
of
am
ole
cu
lein
flu
en
ce
sits
ab
ility
tofo
rmte
mp
ora
ryd
ipo
les.
Lo
ng
thin
mo
lecu
les
ca
np
ack
clo
se
rto
ea
ch
oth
er
tha
nm
ole
cu
les
tha
ta
rem
ore
sp
he
rica
l.T
he
big
ge
rth
e's
urf
ace
are
a'
of
am
ole
cu
le,
the
gre
ate
rth
eva
nd
er
Wa
al's
forc
es
will
be
an
dth
eh
igh
er
the
me
ltin
ga
nd
bo
ilin
gp
oin
tso
fth
eco
mp
ou
nd
will
be
.
�V
an
de
rW
aa
l'sfo
rce
sare
of
the
ord
er
of
1%
of
the
str
en
gth
ofa
co
va
len
tb
on
d.
Hom
onucle
ar
mole
cule
s,
such a
s iodin
e,
develo
p
tem
pora
ry d
ipole
s d
ue t
o
natu
ral fluctu
ations o
f ele
ctr
on
density w
ithin
the m
ole
cule
Hete
ronucle
ar
mole
cule
s,
such a
s H
-Cl have p
erm
anent
dip
ole
s t
hat att
ract
the o
pposite
pole
in o
ther
mole
cule
s.
Th
ed
ipo
les
ca
nb
efo
rme
da
sa
resu
lto
fu
nb
ala
nced
dis
trib
utio
n
of
ele
ctr
ons
ina
sym
ettri
ca
lm
ole
cu
les.
Th
isis
cause
db
yth
e
insta
nta
neo
us
loca
tio
no
fa
few
more
ele
ctr
on
so
none
sid
eo
fth
e
nu
cle
us
tha
no
nth
eo
the
r.
sym
metr
icasym
metr
ic
Th
ere
fore
ato
ms
or
mo
lecu
les
co
nta
inin
gd
ipo
les
are
att
racte
dT
he
refo
rea
tom
so
rm
ole
cu
les
co
nta
inin
gd
ipo
les
are
att
racte
d
toe
ach
oth
er
by
ele
ctr
osta
tic
forc
es.
Display a marked
attractive forces
Noattractionisproduced
�T
he
se
forc
es
are
du
eto
the
ele
ctr
osta
tic
att
ractio
n
be
twe
en
the
nu
cle
us
of
on
ea
tom
an
dth
ee
lectr
on
so
f
the
oth
er.
�V
an
de
r w
aa
ls in
tera
ctio
n o
ccu
rs g
en
era
lly b
etw
ee
n
�V
an
de
r w
aa
ls in
tera
ctio
n o
ccu
rs g
en
era
lly b
etw
ee
n
ato
ms w
hic
h h
ave
no
ble
ga
s c
on
fig
ura
tio
n.
va
n d
er
wa
als
bo
nd
ing
5 5 5 5 5 5 5 5 – –––– –––HYDROGEN BONDING
HYDROGEN BONDING
HYDROGEN BONDING
HYDROGEN BONDING
HYDROGEN BONDING
HYDROGEN BONDING
HYDROGEN BONDING
HYDROGEN BONDING
�A
hyd
rog
en
ato
m,
ha
vin
go
ne
ele
ctr
on
,ca
nb
eco
va
len
tly
bo
nd
ed
too
nly
on
ea
tom
.H
ow
eve
r,th
eh
yd
rog
en
ato
m
ca
nin
vo
lve
itse
lfin
an
ad
ditio
na
le
lectr
osta
tic
bon
dw
ith
a
se
co
nd
ato
mo
fh
igh
lye
lectr
on
eg
ative
ch
ara
cte
rsu
ch
as
flu
ori
ne
or
oxyg
en
.T
his
se
co
nd
bo
nd
pe
rmits
ahydrogen
bond
be
twe
en
two
ato
ms
or
str
ucu
res.
bond
be
twe
en
two
ato
ms
or
str
ucu
res.
�T
he
str
en
gth
of
hyd
rog
en
bo
nd
ing
va
rie
sfr
om
0.1
to0
.5
ev/a
tom
.
�H
yd
rog
en
bo
nd
sco
nn
ect
wa
ter
mo
lecu
les
ino
rdin
ary
ice
.
Hyd
rog
en
bo
nd
ing
isa
lso
ve
ry
imp
ort
an
tin
pro
tein
sa
nd
nu
cle
ica
cid
sa
nd
the
refo
rein
life
pro
ce
sse
s.
